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Sample records for 86rb vblizi porogov

  1. Effect of selenite on 86Rb uptake by rat lens

    The effect was observed in vitro of selenite on the uptake of 86Rb by the lens in two weeks old and adult rats. Also measured was the uptake of 86Rb by the lens in vitro in 30-days old rats with cataracts induced by the administration of selenite at day 14 after birth and in control animals of the same age. Selenite in a concentration of 0.4 mM and more caused an insignificant decrease in 86Rb uptake by the lens in adult rats while in the lens of young rats the uptake decreased significantly already at concentrations lower by two orders. Lenses with cataracts took up significantly less 86Rb than transparent lenses; body weight, the weight of the fresh lens and its dry mass decreased while the water content in the lens was higher as compared with control groups. (author). 2 tabs., 26 refs

  2. Release of 86Rb from rat submandibular gland slices: relation to sodium pump activity

    Slices of rat submandibular gland were preloaded with 86Rb, an isotope that can substitute for K+ in the K+ release process. The efflux of 86Rb was monitored in a superfusion apparatus that efficiently removed the 86Rb as it exited from the tissue slices. Carbachol and the calcium ionophore A23187 activated a calcium-dependent increase in 86Rb efflux. Dibutyryl cGMP had no detectable effect on 86Rb efflux in contrast to its activation of ouabain-sensitive uptake of 86Rb observed in an earlier study. The stimulated release of 86Rb was not dependent on the presence of either sodium or chloride ion. When 86Rb efflux was stimulated by carbachol, the efflux rate returned toward the basal rate after a few minutes of exposure to carbachol in the medium. If ouabain was then introduced into the superfusate, a large increase in efflux was stimulated. In the absence of carbachol, only a small increase in 86Rb efflux was stimulated by ouabain. The effect of ouabain indicates that there was a substantial recycling of 86Rb between the release and uptake processes in the extracellular space of the tissue slice. The significance of this observation is discussed

  3. Loss of receptor-mediated 86Rb efflux from pig aortic endothelial cells in culture.

    Ager, A.; Martin, W

    1983-01-01

    The responsiveness of freshly-isolated and subcultured pig aortic endothelial cells to adenosine triphosphate (ATP), bradykinin and ionophore A23187 was compared by monitoring agonist-induced 86Rb efflux. ATP, bradykinin and ionophore A23187 stimulated 86Rb efflux from freshly-isolated cells. ATP and bradykinin, which act via specific receptors, were less effective at inducing 86Rb efflux from subcultured cells but ionophore A23187 was as effective on subcultured as on freshly-isolated cells....

  4. 86Rb Distribution in the Lung of the Rabbit with Pneumothorax

    86Rb uptake of some organs and tissues, eg. both lungs, both renal cortices. small intestine, liver and skeletal muscle were studied in the control and the rabbit subjected to pneumothorax. 86Rb in the form of chloride mixed with physiological saline was intravenously injected. The doses were 100 μc for a rabbit. The rabbits were sacrificed at intervals of 10, 20, 40, and 60 seconds after the injection of 86Rb, by the injection of saturated KCI solution. After scarification, the organ and tissue sample were quickly removed. 86Rb uptake in gm of the organs and tissues were measured. On the basis of uptake value, administered doses and body weight, % dose/gm tissues per 200 gm body weight was calculated. Followings were the results: 1. Pneumothorax resulted in a marked elevation in 86Rb uptake value of collapsed lung and returned to normal level lately. 2. Contralateral lung of pneumothorax also showed marked elevation in 86Rb uptake value and recovered to normal level. 3. Initial 86Rb uptake value of liver, small intestine of the rabbit with pneumothorax showed some elevation as compared to control, but that of late stage were similar with control. 4. Local blood flow determination by means of 86Rb uptake were inadequate in the collapsed lung of pneumothorax. 5. It was suggested that the mechanism for the initial elevation of 86Rb uptake value in each organs and tissue were different from each other.

  5. Leiurus quinquestriatus venom inhibits BRL 34915-induced 86Rb+ efflux from the rat portal vein

    The effect of the crude venom of the Israeli scorpion Leiurus quinquestriatus hebraeus on the 86Rb+ efflux stimulated by the K+ channel opener BRL 34915 in the rat portal vein was examined. Applied alone, the venom greatly increased the spontaneous mechanical activity of and the concomitant 86Rb+ efflux from the vessel. When the excitability of the vein was suppressed by the dihydropyridine calcium antagonist, PN 200-110, the 86Rb+ efflux stimulated by BRL 34915 could be shown to be inhibited by the venom. From the concentration dependence of this inhibition an IC50 value of 0.17 +/- 0.01 mg/ml was estimated. This venom is thus the most potent blocker of BRL 34915-evoked 86Rb+ efflux reported so far. 17 references, 2 figures

  6. The uptake of 86Rb+ into photoautotrophic mesophyll cells of Papaver somniferum

    Uptake of 86Rb+, used as a tracer for potassium, into isolated photoautotrophic mesophyll cells of Papaver somniferum was weakly but consistently stimulated in the light. It showed mono-phasic saturation kinetics with a pH optimum of 7.0, a Vsub(max) of 6.7 μmol mg-1 Chl x h-1 and a Ksub(m) of 2.7 mmol l-1. Different anions as Cl-, NO3- and PO43- had no effects on 86Rb+ uptake. Sodium ions influenced Rb+-uptake very weakly, indicating a high K+ -specificity of the mesophyll cell plasmalemma. Fusicoccin stimulated 86Rb+ -uptake strongly whereas abscisic acid inhibited uptake only following preincubation for two hours. Nitrite, CCCP and Dio-9 inhibited 86Rb+-uptake which gives evidence that this process is dependent on intact pH-gradients within the cells and on ATP-formation. (orig.)

  7. Inhibition of white light of 86Rb+ absorption in the root apex of corn

    Measurements of cell lengths made at 0.5 millimeter intervals in median longitudinal sections of the primary roots of corn (Zea mays) were used to construct a growth curve. The region 1.5 to 4.0 millimeters from the apex contained the largest number of elongating cells. Absorption of 86Rb+ was measured using intact, dark-grown corn seedlings. Following uptake and exchange, the terminal 8.0 millimeters of each root was cut into four 2.0 millimeter segments. Maximum 86Rb+ uptake occurred in the region from 0.0 to 4.0 millimeter from the root tip. Washing the intact primary root in fresh 2.0 millimolar CaSO4 for 2 hours prior to uptake augmented the rate of 86Rb+ uptake in all regions. Illumination with white light during washing caused a reduction of 86Rb+ uptake as compared with controls washing in darkness, and the region of greatest light response was the region of elongation. Removal of the coleoptile prior to washing did not prevent the light inhibition of subsequent 86Rb+ uptake. Removal of the root cap prior to washing in light partially reversed the light-induced inhibition of the washing response

  8. Environmental effects on energy metabolism and 86Rb elimination rates of fishes

    Relationships between energy metabolism and the turnover rates of number of important chemical and radiological elements (particularly the Group IA alkali metals: K, Rb, and Cs) have been observed in fishes. Using response surface statistics and fractional factorial ANOVA, the author examined the relative influences of temperature, salinity, food intake rate, mass, and their first order interactions on routine energy metabolism and 86Rb elimination rates. Routine metabolic rates were increased primarily by increased temperature and salinity, with a strong body mass effect and a significant effect of food intake. 86Rb elimination rates were increased primarily by increased temperature and salinity. There were no interactive effects between mass and either temperature or salinity for either routine energy metabolism or 86Rb elimination rates. There was a significant interaction effect between temperature and salinity on routine energy metabolism rates, but not on 86Rb elimination. The authors also observed a relationship between routine energy metabolism and 86Rb elimination rates that may possibly be exploited as a means of estimating energy metabolic rates of fishes in the field. The statistical techniques used in this experiment have broad potential applications in assessing the contributions of combinations of environmental variables on contaminant kinetics, as well as in multiple toxicity testing, in that they greatly simplify experimental designs compared with traditional full-factorial methods

  9. Transport of 86Rb+ in corn leaves as influenced by some growth substances

    The transport of 86Rb+ supplied to the middle of young corn leaves was scanned by means of a modified chromatogram scanner and it was found that the movement towards the base was larger than to the apex of both intact and excised leaves. Application of 25 ppm of ABA (abscisic acid) or ethrel (2-chloroethane phosphonic acid) did not affect the pattern of transport. However, the growth substances tested, viz, ABA, ethrel, GA3 and IAA generally enhanced the rate of 86Rb+ transport towards the base of the leaf. (orig.)

  10. Leakage of 86Rb+ after ultraviolet irradiation of Escherichia coli K-12

    Stationary phase cultures of a DNA repair proficient Escherichia coli K-12 strain showed a release of intracellular material as assessed by three different methods (260 nm absorption; (methyl-3H) thymidine leakage and 86Rb+ leakage) after broad-band near-UV radiation but not after far-UV (254 nm) radiation. As a control response for membrane damage to cells, this leakage of intracellular material was also determined by each method after mild heat (520C) treatment of E. coli K-12. An action spectrum for the release of 86Rb+ from E. coli K-12 after monochromatic irradiation (254 to 405 nm) is also presented. The action spectrum for lethality (F37 values) shows that leakage of 86Rb+ occurs at fluences around those causing inactivation at wavelengths above 305 nm. In contrast, at wavelengths below 305 nm, leakage of 86Rb+ from irradiated cells can be induced but only at fluences significantly greater than was required to cause cell inactivation. These results indicate that near-UV radiation can damage the cell's permeability barrier which may be significant in causing cell death, whereas the effect is not significant in causing cell death by far-UV radiation where DNA is known to be the main cause of lethality. (author)

  11. Vectorial (transcellular) transport of potassium (86Rb+) by cultured Sertoli cells

    Sertoli cells from rats aged 25 days were grown on Millipore filters (pore diameter 0.5 micron) for 7 days and were then used for determination of transport of 86Rb+ through the cells (base to apex); this procedure is referred to as measuring transcellular or vectorial transport. Sertoli cells were also used to measure apical efflux of 86Rb+ by loading the cells with the isotope to steady state and then incubating cells so that the apical surfaces were in contact with medium not containing 86Rb+, from which samples were taken. Basal efflux was measured in the same way except that the opposite surface of the cells was in contact with the medium. Cells grown on filters treated with collagen IV plus fibronectin showed transcellular transport of 86Rb+; t1/2 for equilibration across the cells was 9-12 min. The rate of transport was accelerated by addition of (Bu)2cAMP, forskolin, or FSH to the incubation medium. Half-maximal responses were seen with (Bu)2cAMP at 0.2 mM and with forskolin at 20 microM. Apical efflux (t1/2 9.8 +/- 2.1 min) was not influenced by the presence or absence of K+ in the medium nor by azide or (Bu)2cAMP. Basal efflux showed similar values for t1/2 in the presence of K+ (9.7 +/- 1.9 min) and values of 21.4 +/- 4.2 min in the absence of K+. Vectorial transport of 86Rb+ by these cells may account for the K+ gradient seen in the seminiferous tubule and appears to result from a basolateral potassium pump together with an apical membrane that is permeable to K+

  12. Uptake of 32P and 86Rb as influenced by temperature, transpiration suppress and shading treatment in rice plants

    This study was carried out to know the uptake pattern of phosphorous and potassium in rice plants using by two radioisotopes, 32P and 86Rb as tracers for two years, 1987 and 1988. Rice plants were grown in the hydroponic culture with Yoshida's solution, and treated with different temperatures, transpiration suppress, shading, and phosphorous and potassium deletions. The uptake amount of 32P and 86Rb were increased with the increasing temperature in root sphere of rice plant, particularly remarkable increase of 86Rb uptake at 35deg C. The uptake of 32P tended to be promoted at the treatment of low air-high water temperature (17-30deg C), while that of 86Rb was not significantly differenced from different temperature treatments. The effect of transpiration on the uptake of 32P and 86Rb was extremely low. This phenomenon may suggest that the absorption be depending on active uptake rather than passive one by transpiration stream. The total carbohydrate contents of rice root were decreased by shading treatment, resulting significant reduction in the uptake of 32P and 86Rb. The uptake of 86Rb was remarkably increased in the treatment of potassium deletion, but that of 32P was not significantly increased in the delection of phosphorous

  13. Burn-up cross sections of 51Cr, 59Fe, 65Zn, 86Rb, 103Ru

    Targets of Cr, Fe, Zn, Rb, and Ru were irradiated in the hydraulic tube of the Oak Ridge HFIR reactor at a neutron flux of 2.6 x 1015 n/cm2sec for 1 day and 20 days. The reactor burn-up cross sections (in barns) of the radioactive product nuclides are: 51Cr, 59Fe, 65Zn, 60 +- 30; 86Rb, 103Ru, <20

  14. Comparison of effects of cromakalim and pinacidil on mechanical activity and 86Rb efflux in dog coronary arteries

    Effects of two K+ channel openers, cromakalim and pinacidil, on mechanical activity and on 86Rb efflux were compared in strips of dog coronary arteries. Cromakalim and pinacidil produced the relaxation in 20.9 mM K(+)-contracted strips with a pD2 of 6.53 and 5.95, respectively. In 65.9 mM K(+)-contracted strips, high concentrations of pinacidil, but not cromakalim, produced relaxation. Ca+(+)-induced contractions in 80 mM K(+)-depolarized strips were also inhibited by pinacidil but not by cromakalim. Glibenclamide, a blocker of ATP-regulated K+ (KATP) channels, competitively antagonized the relaxant responses to cromakalim with a pA2 value of 7.62. However, the antagonism by glibenclamide of the relaxant responses to pinacidil was not a typical competitive type, suggesting the contribution of other effects than the KATP channel opening activity to the relaxant effects of pinacidil. In resting strips preloaded with 86Rb, cromakalim and pinacidil increased the basal 86Rb efflux in a dose-dependent manner. The increase in the 86Rb efflux induced by cromakalim was greater than that by pinacidil. When the effects of cromakalim and pinacidil on the 86Rb efflux were determined in the 20.9 or 65.9 mM K(+)-contracted strips, both drugs increased the 86Rb efflux. Under the same conditions nifedipine, a Ca(+)+ channel blocker, produced the relaxation that is accompanied by the decrease in 86Rb efflux. The increase in the 86Rb efflux induced by cromakalim was much greater than that by pinacidil

  15. Ba2+-inhibitable 86Rb+ fluxes across membranes of vesicles from toad urinary bladder

    86Rb+ fluxes have been measured in suspensions of vesicles prepared from the epithelium of toad urinary bladder. A readily measurable barium-sensitive, ouabain-insensitive component has been identified; the concentration of external Ba2+ required for half-maximal inhibition was 0.6 mM. The effects of externally added cations on 86Rb+ influx and efflux have established that this pathway is conductive, with a selectivity for K+, Rb+ and Cs+ over Na+ and Li+. The Rb+ uptake is inversely dependent on external pH, but not significantly affected by internal Ca2+ or external amiloride, quinine, quinidine or lidocaine. It is likely, albeit not yet certain, that the conductive Rb+ pathway is incorporated in basolateral vesicles oriented right-side-out. It is also not yet clear whether this pathway comprises the principle basolateral K+ channel in vivo, and that its properties have been unchanged during the preparative procedures. Subject to these caveats, the data suggest that the inhibition by quinidine of Na+ transport across toad bladder does not arise primarily from membrane depolarization produced by a direct blockage of the basolateral channels. It now seems more likely that the quinidine-induced elevation of intracellular Ca2+ activity directly blocks apical Na+ entry

  16. Characterization of Ca(2+)-activated 86Rb+ fluxes in rat C6 glioma cells: a system for identifying novel IKCa-channel toxins.

    de-Allie, F. A.; Bolsover, S. R.; Nowicky, A. V.; Strong, P N

    1996-01-01

    1. The pharmacological characteristics of a putative Ca2+ activated K+ channel (IKCa channel) in rat glioma C6 cells were studied in the presence of the Ca2+ ionophore, ionomycin and various K+ channel blockers, 86Rb+ being used as a radioisotopic tracer for K+. 2. The resting 86Rb+ influx into C6 cells was 318 +/- 20 pmol s-1. The threshold for ionomycin activation of 86Rb+ influx was approx. 100 nM. At ionomycin concentrations above the activation threshold, the initial rate of 86Rb+ influx...

  17. Erythrocyte sodium concentration and 86Rb uptake in weanling Dahl rats

    Alterations in Na, K ATPase pump activity as well as erythrocyte (RBC) intracellular sodium concentration (Nai) have been demonstrated in humans and rats with established hypertension. The contribution of hypertension itself to these changes is unclear. Accordingly, we investigated RBC ion transport and plasma ouabain-like factor (OLF) in four- to five-week old normotensive Dahl salt-sensitive (DS) and salt-resistant (DR) rats on low salt diet. Although both strains were normotensive, systolic blood pressure (SBP) of DS (123 ± 2 mm Hg) was higher than that of DR (116 ± 1 mm Hg). No interstrain difference was evident in RBC pump activity measured as ouabain-sensitive 86rubidium (86Rb) uptake (DS = 0.277 ± .030 and DR = 0.271 ± .029 mumol/10(9)RBC/h) even though RBC Nai was greater in DS than DR (14.9 ± 2.0 v 10.7 ± 1.0 mEq/L; P less than 0.05). Plasma OLF was higher in DS than DR (28.9 ± 4.7 v 16.5 ± 2.3 pmol/mL; P less than 0.05), but did not correlate with RBC pump activity in either strain. RBC Nai was directly correlated with pump activity in DS (r = 0.84, P less than 0.01) and demonstrated a trend to correlate in DR (r = 0.71, P = 0.07). RBC Nai was also directly correlated with SBP in DR (r = 0.73, P less than 0.05) and DS (r = 0.70, P = 0.05). We conclude that RBC Nai is genetically determined in Dahl rats and is elevated in normotensive DS who are at risk for hypertension development

  18. The uptake, distribution and translocation of 86Rb in alfalfa plants susceptible and resistant to the bacterial wilt and the effect of Corynebacterium insidiosum upon these processes

    Alfalfa (Medicago sativa L.) plants susceptible (S) and resistant (R) to bacterial wilt were fed via roots with a nutrient solution labelled with 86Rb+, at different times after inoculation with Corynebacterium insidiosum (McCull.) H.L. Jens. The infection did not affect 86Rb+ uptake per plant in the course of a 14-day-period following inoculation; however, it affected its distribution differently in the S- and the R-plants. 86Rb+ uptake significantly decreased due to the infection in the S-plants on the day 49 after inoculation (a 4-h-exposure to 86Rb+), with the ions more slowly translocated to the shoots in diseased S-plants than in diseased R-plants. Likely factors causing these effects and their relationship to alfalfa resistance to bacterial wilt are discussed. (author)

  19. Effect of ultraviolet radiation on accumulation and leakage of 86Rb+ in guard cells of Vicia faba

    The effects of UV-C (254 nm), UV-A (365 nm) and broad-band UV (280–380 nm) on guard cells of Vicia faba L. cv. Long Pod were investigated in the presence of white light (450 μmol m−2 s−1). UV-C (7 μmol m−2 s−1) was found to cause leakage of 86Rb+ from guard cells, while UV-A (0.3 μmol m−2 s−1) stimulated increased uptake in these cells. A relatively small stimulatory effect was observed by broad-band UV (3 μmol m−2 s−1) during the first 30 min of irradiation with an apparent equilibration of influx and efflux thereafter. Leakage of 86Rb+ from guard cells continued despite the removal of UV-C and an increase in the amount of white light from 450 to 1500 μmol m−2 s−1, suggesting that membranes were irreversibly damaged. Irradiation of guard cells with UV-C for 30, 45 and 90 min indicated that these cells began to be affected already by 30 min UV-C irradiation. (author)

  20. Effect of chronic hypoxia on 45Ca and 86Rb uptake in aortic smooth muscle from spontaneously hypertensive rats (SHR)

    The effect of chronic hypobaric hypoxia equivalent to a simulated high altitude of 4000 m was investigated on the Ca2+ and Rb+ uptake in vascular smooth muscle. The decline in systolic blood pressure in SHR due to hypoxia was associated with a significant decrease in 45Ca uptake and ouabain-insensitive 86Rb uptake as well as the tissue Ca2+ and K+ content. It seems likely that the reduction of the higher vascular tone in SHR by chronic hypoxia is due to the alteration of the transmembrane ion fluxes in the vascular smooth muscle cells. However, the meaning and the nature of the active and passive ion fluxes involved in this problem remains to be clarified. (author)

  1. The effect of sodium ions on the light-induced 86Rb release from the isolated crayfish retina

    The effect of low external Na+ concentrations on the light-induced K+ release from crayfish photoreceptor cells was tested by labelling intracellular K+ with the isotope 86Rb. The amount of isotope released per light, stimulus is roughly proportional to the external Na+ concentration if the osmolarity is kept constant by replacing Na+ with Tris, choline or sucrose. When sucrose is used to replace the depleted Na+ the light-induced K+ release is a linear function of the external Na+ concentration and is reduced by approx. 95% at an external Na+ concentration of 5 mmol/l. For choline and Tris substitutions the relationships are less clear but at Na+ concentrations + release is smaller in a Tris solution and larger in a choline solution. It is suggested that the light-induced K+ release is due mainly to an activation of voltage sensitive K+ channels. (orig.)

  2. Calcium accumulated by sickle cell anemia red cells does not affect their potassium (86Rb+) flux components

    We investigate here the hypothesis that the high Ca content of sickle cell anemia (SS) red cells may produce a sustained activation of the Ca2+-dependent K+ permeability (Gardos effect) and that the particularly high Ca levels in the dense SS cell fraction rich in irreversibly sickled cells (ISCs) might account for the Na pump inhibition observed in these cells. We measured active and passive 86Rb+ influx (as a marker for K+) in density-fractionated SS cells before and after extraction of their excess Ca by exposure to the Ca ionophore (A23187) and ethylene glycol tetra-acetic acid and with or without adenosine triphosphate depletion or addition of quinine. None of these maneuvers revealed any evidence of a Ca2+-dependent K leak in SS discocytes or dense cells. Na pump inhibition in the dense SS cells was associated with normal activation by external K+ and a low Vmax that persisted after Ca extraction from the cells. These results are consistent with our recent findings that the excess Ca in these cells is compartmentalized in intracellular inside-out vesicles and unavailable as free Ca2+ to the inner membrane surface. Although the steady-state free cytoplasmic Ca2+ in oxygenated SS cells must be below the levels needed to activate the K+ channel, possible brief activation of the channels of some SS cells resulting from transient elevations of cell Ca2+ during deoxygenation-induced sickling cannot be excluded. The dense, ISC-rich SS cell fraction showed a Ca2+-independent increase in the ouabain-resistant, nonsaturable component of 86Rb+ influx that, if uncompensated by Na+ gain, could contribute to the dehydration of these cells

  3. Evaluation of crop residues on potassium kinetics in an acid soil and potassium use efficiency in potato-garlic sequence using tracer 86Rb

    Greenhouse and laboratory studies were conducted on an acid soil in order to evaluate the role of two crop residues i.e. paddy and wheat along with farmyard manure on potassium kinetics and its availability in the potato-garlic sequence using tracer 86Rb. Under rapid equilibrium, application of crop residues of paddy, wheat straw and FYM were able to enhance soil pH and organic carbon content. In addition, their application helped in enhancing soil K availability indices like water soluble, available and non-exchangeable -K. This was further augmented by the Q/I studies using 86Rb where application of organic residues helped in lowering the potassium buffering capacity of the soil. Greenhouse study supplemented the results obtained from laboratory study where application of crop residues/FYM were able to improve the potato yield significantly and maintained higher concentration of K in potato leaf at early growth stages. A significant correlation was obtained between leaf K and haulms-K with that of 86Rb activities in potato leaf at 35 days and 86Rb absorbed in the haulms, respectively. Residues/ FYM and PK application to potato left sufficient residual effect on succeeding garlic crop. In potato-garlic sequence, K recovery was highest with FYM while N and P recoveries were higher with wheat residues. The nutrient recoveries with PK application followed law of diminishing returns. (author)

  4. sup 86 Rb(K) influx and ( sup 3 H)ouabain binding by human platelets: Evidence for beta-adrenergic stimulation of Na-K ATPase activity

    Turaihi, K.; Khokher, M.A.; Barradas, M.A.; Mikhailidis, D.P.; Dandona, P. (Royal Free Hospital and School of Medicine, London (England))

    1989-08-01

    Although active transport of potassium into human platelets has been demonstrated previously, there is hitherto no evidence that human platelets have an ouabain-inhibitable Na-K ATPase in their membrane. The present study demonstrates active rubidium (used as an index of potassium influx), {sup 86}Rb(K), influx into platelets, inhibitable by ouabain, and also demonstrates the presence of specific ({sup 3}H)ouabain binding by the human platelet. This {sup 86}Rb(K) influx was stimulated by adrenaline, isoprenaline, and salbutamol, but noradrenaline caused a mild inhibition. Active {sup 86}Rb(K) influx by platelets was inhibited markedly by timolol, mildly by atenolol, but not by phentolamine. Therefore, active {sup 86}Rb(K) influx in human platelets is enhanced by stimulation of beta adrenoceptors of the beta 2 subtype. The platelet may therefore replace the leukocyte in future studies of Na-K ATPase activity. This would be a considerable advantage in view of the ease and rapidity of preparation of platelets.

  5. Concentration-response relationship of {alpha}{sub 1}-adrenoceptor-stimulated increase of {sup 86}Rb{sup +} efflux in rat heart

    Andersen, G.Oe.; Enger, M.; Skomedal, T.; Osnes, J.B. [Univ. of Oslo, Dept. of Pharmacology (Norway)

    1996-10-01

    The aim of the present study was to establish a concentration-response relationship for the {alpha}{sub 1}-adrenoceptor mediated increase of{sup 86}Rb{sup +} efflux, and to characterize the sensitivity of this response to the selective {alpha}{sub 1}-adrenoceptor antagonist prazosin. Isolated rat hearts were perfused retrogradely at constant flow and at 31 deg. Timolol (10{sup -}26 mol/l) was used to block {beta}-adrenoceptors. After a loading period with {sup 86}Rb{sup +} and 55 min. washout, the hearts were exposed to phenylephrine in a concentration range from 3x10{sup -8} mol/l to 10{sup -4} mol/l. Control experiments comparing the effects of {alpha}{sub 1}-adrenoceptor stimulation on {sup 86}Rb{sup +} efflux and {sup 42}K{sup +} efflux were performed. {alpha}{sub 1}-Adrenoceptor stimulation increased the {sup 86}Rb{sup +} efflux with a pD{sub 2}=6.35{+-}0.20 (mean{+-}S.E.M.) The maximal response to phenylephrine was 22.5{+-}2.0% (mean{+-}S.E.M.) of the control values. The concentration-response curve was shifted to higher concentration of agonist in the presence of the {alpha}{sub 1}-adrenoceptor antagonist prazosin (3x10{sup -10} mol/l). The calculated inhibition constant for prazosin was 6.1x10{sup -11} mol/l. {sup 86}Rb{sup +} was found to be a suitable K{sup +} analogue in the study of relative changes in K{sup +} efflux concentration-dependently. A high sensitivity to prazosin confirmed the involvement of the {alpha}{sub 1}-adrenoceptor population. (au) 37 refs.

  6. Alterations by glyburide of effects of BRL 34915 and P 1060 on contraction, 86Rb efflux and the maxi-K+ channel in rat portal vein

    Effects of the K+ channel blocking agent, glyburide, on the actions of two K+ channel openers, BRL 34915 (cromakalim) and P 1060 (Leo), a potent pinacidil derivative (N-(t-butyl)-N double-prime-cyano-N'-3-pyridyl-guanidine), were ascertained. Tension responses and 86Rb fluxes in rat portal vein strips and single channel electrophysiological recordings in enzymatically dissociated rat portal vein cells were obtained. Glyburide (0.3 microM) increased spontaneous contractile activity and caused concentration-dependent shifts in the relaxation responses to BRL 34915 and P 1060. Increases in 86Rb efflux were obtained only at much higher concentrations of BRL 34915 or P 1060, and these increases were blocked only at higher concentrations of glyburide (5.0 microM). BRL 34915 and P 1060 specifically increase the open-state probability of the Ca+(+)-activated K+ (maxi-K+) channel, and these actions are blocked by glyburide and also by charybdotoxin. Changes in single channel activity and contractile responsiveness occur at similar concentrations of agonists and antagonists. Thus, the membrane channel in rat portal vein affected by glyburide, BRL 34915 and P 1060 appears to be the Ca+(+)-activated maxi-K+ channel (that does not show ATP dependence under the conditions of these experiments). Concentrations of agonists and antagonists effective on maxi-K+ channel activity correspond to those affecting contractile responsiveness and are lower than those eliciting changes in 86Rb flux

  7. Alteration of alpha 1 Na+,K(+)-ATPase 86Rb+ influx by a single amino acid substitution

    The sodium- and potassium-dependent adenosine triphosphatase (Na+,K(+)-ATPase) maintains the transmembrane Na+ gradient to which is coupled all active cellular transport systems. The R and S alleles of the gene encoding the Na+,K(+)-ATPase alpha 1 subunit isoform were identified in Dahl salt-resistant (DR) and Dahl salt-sensitive (DS) rats, respectively. Characterization of the S allele-specific Na+,K(+)-ATPase alpha 1 complementary DNA identified a leucine substitution of glutamine at position 276. This mutation alters the hydropathy profile of a region in proximity to T3(Na), the trypsin-sensitive site that is only detected in the presence of Na+. This mutation causes a decrease in the rubidium-86 influx of S allele-specific sodium pumps, thus marking a domain in the Na+,K(+)-ATPase alpha subunit important for K+ transport, and supporting the hypothesis of a putative role of these pumps in hypertension

  8. Nutrient utilization by crops and its influence on cotton-wheat double cropping using 15N, 32P and 86Rb

    Double crop interplanting of cotton-wheat is the main cultivation system of cotton fields in the Yangtze Valley of China. The relationship (nutrient absorption and utilization) between the two crops is the key problem in fertilizer management for achieving high yields of both grain and cotton. The results of a research carried out in a microplot experiment for three years are presented. 1 ref., 6 tabs

  9. Ouabain enhancement of compound 48/80 induced histamine secretion from rat peritoneal mast cells: dependence on extracellular sodium

    Knudsen, T; Bertelsen, Niels Haldor; Johansen, Torben

    1992-01-01

    Purified populations of rat peritoneal mast cells were used to study the effect of ouabain on compound 48/80-induced histamine secretion and on 86Rb+ uptake. 86Rb+ was used as a tracer for extracellular K+. The calculated value of the ouabain-sensitive uptake of K+ and 86Rb+ was considered a meas...

  10. Is activation of the Na+K+ pump necessary for NGF-mediated neuronal survival

    The ability of nerve growth factor to cause rapid activation of the Na+K+ pump of its responsive cells was examined by measuring the uptake of 86Rb+. A significant increase in 86Rb+ uptake in E8 chick dorsal root ganglion sensory neurons after NGF treatment was seen only if the cells had been damaged during the preparation procedure. Such damaged cells could not survive in culture in the presence of NGF, and undamaged cells that did survive in response to NGF exhibited no increased 86Rb+ uptake rate. Furthermore, cultured calf adrenal medullary cells did not show an increase in 86Rb+ uptake after treatment with NGF, although these cells respond to NGF with an increased synthesis of catecholaminergic enzymes. These results are incompatible with the hypothesis that the mechanism of action of NGF that promotes neuronal survival and enzyme induction results from an initial stimulation of the Na+K+ pump

  11. GABA/sub B/ receptor activation inhibits Ca2+-activated potassium channels in synaptosomes: involvement of G-proteins

    86Rb-efflux assay from preloaded synaptosomes of rat cerebral cortex was developed to study the effect of GABA/sub B/ receptor agonist baclofen on Ca2+-activated K+-channels. Depolarization of 86Rb-loaded synaptosomes in physiological buffer increased Ca2+-activated 86Rb-efflux by 400%. The 86Rb-efflux was blocked by quinine sulfate, tetraethylammonium, and La3+ indicating the involvement of Ca2+-activated K+-channels. (-)Baclofen inhibited Ca2+-activated 86Rb-efflux in a stereospecific manner. The inhibitory effect of (-)baclofen was mediated by GABA/sub B/ receptor activation, since it was blocked by GABA/sub B/ antagonist phaclofen, but not by bicuculline. Further, pertussis toxin also blocked the ability of baclofen or depolarizing action to affect Ca2+-activated K+-channels. These results suggest that baclofen inhibits Ca2+-activated K+-channels in synaptosomes and these channels are regulated by G-proteins. This assay may provide an ideal in vitro model to study GABA/sub B/ receptor pharmacology

  12. GABA/sub B/ receptor activation inhibits Ca/sup 2 +/-activated potassium channels in synaptosomes: involvement of G-proteins

    Ticku, M.K.; Delgado, A.

    1989-01-01

    /sup 86/Rb-efflux assay from preloaded synaptosomes of rat cerebral cortex was developed to study the effect of GABA/sub B/ receptor agonist baclofen on Ca/sup 2 +/-activated K/sup +/-channels. Depolarization of /sup 86/Rb-loaded synaptosomes in physiological buffer increased Ca/sup 2 +/-activated /sup 86/Rb-efflux by 400%. The /sup 86/Rb-efflux was blocked by quinine sulfate, tetraethylammonium, and La/sup 3 +/ indicating the involvement of Ca/sup 2 +/-activated K/sup +/-channels. (-)Baclofen inhibited Ca/sup 2 +/-activated /sup 86/Rb-efflux in a stereospecific manner. The inhibitory effect of (-)baclofen was mediated by GABA/sub B/ receptor activation, since it was blocked by GABA/sub B/ antagonist phaclofen, but not by bicuculline. Further, pertussis toxin also blocked the ability of baclofen or depolarizing action to affect Ca/sup 2 +/-activated K/sup +/-channels. These results suggest that baclofen inhibits Ca/sup 2 +/-activated K/sup +/-channels in synaptosomes and these channels are regulated by G-proteins. This assay may provide an ideal in vitro model to study GABA/sub B/ receptor pharmacology.

  13. Blood flow measurements in selected oral tissues in dogs using radiolabelled microspheres and rubidium-86

    Radiolabelled microspheres and 86Rb were used in dogs to measure oral tissue blood flow. The tissues studied were mandibular alveolar and basal bone, oral mucosa, gingiva, lip, tongue and soft tissue of hard palate. A suspension of 6 x 106 cerium-141 labelled microspheres, 15 + - 5 μm in diameter was injected into the left ventricle through an arterial catheter in 9 healthy adult dogs. Cardiovascular stability was assessed during the catheterization and injection of microspheres. Following the microsphere injection, 500 μCi of 86Rb was injected intravenously and the animal was killed within 60s. Blood flow measured using 86Rb was not significantly different (p > 0.05) from radiolabelled microsphere flow in mandibular basal bone, oral mucosa and gingiva, suggesting that in these oral tissues nutritional or capillary exchange flow is similar to total blood flow. In mandibular alveolar bone, lip, tongue and soft tissue of hard palate, however, 86Rb measurements were significantly greater (p 86Rb shows promise for continued studies of blood flow in healthy and pathological oral tissues. (author)

  14. Effects of VA mycorrhizas fungus on phosphorus and potassium uptake in tea seedlings

    Tea (Camellia sinensis) seeds were sown on sterilized acidic yellow soil (pH 5.6) in a pot experiment and treated as follows: 1) inoculated with VA mycorrhizas fungus (Glomus citricolum), 2) nonmycorrhizal as control, top dressed with 32P-single superphosphate (M-32P) and 86Rb-rubidium chloride (M-86Rb). The results showed that the percentage of VA mycorrhizas infection was 52.6% for M-32P and 56.7% for M-86Rb. Plant height, dry weight and the uptake of phosphorus and potassium were 2.1 and 1.8 times, 2.4 and 2.5 times, 5.6 and 4.1 times as that of control respectively. The utilization rate of phosphorus and potassium were raised by 14.10% and 17.13% respectively

  15. Changes in cardiac glycoside receptor sites 86 rubidium uptake and intracellular sodium concentrations in the erythrocytes of patients receiving digoxin during the early phases of treatment of cardiac failure in regular rhythm and of atrial fibrillation

    Measurements of the binding of 12-α-[3H]-digoxin to the membranes of intact erythrocytes, erythrocytic 86Rb uptake and intraerythrocytic sodium concentrations have been made in the red cells of patients receiving digoxin in the short-term for atrial fibrillation or cardiac failure in regular rhythm. During the first few days of treatment [3H]-digoxin binding and 86Rb uptake fall and intraerythrocytic sodium concentrations rise. Subsequently parallel fluctuations occur in [3H]-digoxin binding and 86Rb uptake but not in intraerythrocytic sodium concentrations and the significance of the fluctuations is discussed. The values of all three measurements correlate significantly with the response of the heart in sinus rhythm as measured by QS2I. Plasma digoxin concentrations do not correlate with QS2I. (author)

  16. Microinjection study on potassium transport of rat kidney

    Wister rate were divided into the following four groups. (A) control group (B) high-potassium diet group (C) low-potassium diet group (D) nephron population reduction (N.P.R.) group. Microinjection of the artificial solutions containing both 86Rb and 3H-inulin were performed into the proximal and distal convoluted tubules as well as cortical peritubular capillaries in rats undergoing mannitol diuresis. Excretory patterns of these substances were analyzed in successive urine samples. 3H-inulin is entirely recovered in the urine of the experimental kidney following the injection into the proximal and distal tubules. 86Rb is an adequate tracer for potassium and is absorbed into the potassium pool from either proximal tubular injections or peritubular capillaries. 86Rb excreted with a time course similar to that of 3H-inulin is termed as 'direct recovery' and that excreted more slowly, 'delayed recovery'. The 86Rb recoveries which were obtained after proximal injections were independent of the injection site and averaged 9%. Secretion of 86Rb into the urine was stimulate during enhanced K secretion and decreased during reduced K secretion along the distal nephron. Distal tubular injections gave 100% direct recovery in control, high-K diet, and N.P.R. rats. It was apparent that the 86Rb recovery was significantly reduced, although not delayed, in animals deprived of dietary potassium for several weeks. At the collecting duct, the extensive net potassium reabsorption is observed in potassium depleted rats, whereas K absorption might be reduced or even secretion is seemingly taking place in potassium loading rats. In conclution, distal convolution and collecting duct play the major role in the regulation of urinary potassium excretion. (auth.)

  17. Axonal transport of rubidium and thallium in the olfactory nerve of mice

    Following intranasal administration of radioactive 86Rb+ and 201Tl+ in mice, we observed this direct transport via the olfactory nerve pathway. The 86RbCl and 201TlCl solutions were administered to two groups of mice, the unilateral intranasal and intravenous administration groups. After sacrifice, their heads were divided into the right and left side, which were then subdivided into seven parts; the nasal mucosa and brain regions were separated. Following the unilateral intranasal administration, uptake after 6 h by the olfactory bulb was significantly higher on the ipsilateral side (86Rb, 0.7 %dose; 201Tl, 0.5 %dose) than on the contralateral side (86Rb, 0.08 %dose; 201Tl, 0.15 %dose). Moreover, the 86Rb and 201Tl that accumulated in the olfactory bulb were gradually transported to other brain regions of the olfactory tract, the telencephalon and the diencephalon on the side corresponding to the nostril used for administration. Significant differences were observed between the right and left side of the brain regions 6 and 12 h after administration. Further, 201Tl autoradiography clearly showed striped patterns of dense accumulation, localized in the region around the glomerular layer and granule cell layer of the olfactory bulb and around the olfactory cortex. These results provide clear evidence of axonal transport via the olfactory nerve pathway, from nasal cavity to the olfactory bulb, as well as to the olfactory cortex through the synaptic junctions. The olfactory transport of the 86Rb+ and 201Tl+ is thought to represent the behavior of K+ in the olfactory system

  18. Bradykinin and vasopressin stimulate Na/sup +/-K/sup +/-Cl/sup -/ cotransport in cultured endothelial cells

    Brock, T.A.; Brugnara, C.; Canessa, M.; Gimbrone, M.A. Jr.

    1986-06-01

    The authors have characterized a Na/sup +/-K/sup +/-Cl/sup -/ cotransporter in vascular endothelial cells (EC) cultured from different blood vessels and species that is inhibited by the diuretics furosemide and bumentanide. Inward /sup 86/Rb influx transported by the Na/sup +/-K/sup +/ pump in cultured EC from bovine and pig aorta, bovine vena cava, and baboon cephalic vein but not in human umbilical or saphenous vein EC. External Na/sup +/ or Cl/sup -/-stimulated, ouabain-insensitive /sup 86/Rb influx is equal to furosemide or bumetanide-sensitive /sup 86/Rb influx. Ouabain-insensitive /sup 22/Na influx is also partially inhibited by these drugs and stimulated by increasing external K/sup +/ or Cl/sup -/. Net Na/sup +/ extrusion occurs via the Na/sup +/-K/sup +/-Cl/sup -/ cotransporter in the absence of external K/sup +/, whereas net Na/sup +/ influx occurs at higher external K/sup +/. Maximal concentrations (100 nM) of bradykinin and vasopressin increase the initial rate of bumetanide-sensitive /sup 86/Rb influx by approx.60 and 70%. Addition of either ethyleneglycol-bis(..beta..-aminotethylether)-N,N'-tetraacetic acid or LaCl/sub 3/ (to block calcium influx) prevents bradykinin-stimulated /sup 86/Rb influx. When intracellular calcium is elevated using ionomycin (100 nM), a Ca/sup 2 +/ionophore, bumetanide-sensitive /sup 86/Rb influx increases approx.twofold. In contrast, isoproterenol (100 ..mu..M) and forskolin (50 /sup +/M), adenylate cyclase stimulators, decrease furosemide-sensitive /sup 86/Rb influx. Thus in certain types of cultured EC, a Na/sup +/-K/sup +/-Cl/sup -/ cotransporter mediates a fraction of K/sup +/ influx quantitatively as important as the Na/sup +/-K/sup +/ pump (ouabain-sensitive /sup 86/Rb influx) and appears to be modulated by Ca/sup 2 +/ and cyclic nucleotides.

  19. Racial differences in red cell cation transport and their relationship to essential hypertension

    Red cell cation transport has been studied in normotensive and essential hypertensive groups of white and black (West Indian) subjects. In vitro uptake of the potassium analogue 86Rb was measured during short-term incubation of erythrocytes in the presence and absence of ouabain. Sodium pump activity was significantly greater (p less than 0.0005) in white hypertensives than in white normotensives. No such difference was observed between black hypertensive and normotensives. 86Rb uptake was significantly lower in black than in white normotensive individuals; this racial differences was not due to a difference in sodium pump activity

  20. Use of radioisotopes in studying factors responsible for alfalfa resistance to bacterial wiltxng

    Studies are summarized dealing with possible causes of vascular dysfunction and resistance of alfalfa to bacterial wilting caused by Corynebacterium insidiosum (McCull.) H.L. Jens from the physiological and biochemical points of view. Using 32P, 35S, 54Mn, 45Ca, 65Zn, and 86Rb the uptake, distribution, translocation, and metabolism of these elements in plants with a different resistance against diseases were investigated. The possible use is discussed of 86Rb as a tracer of potassium. The results suggest that the resistance of alfalfa to bacterial wilting is probably determined by several factors. (author)

  1. Operation of the Ca-dependent K(Rb)-transport in human lymphocytes

    The transport pathways of the plasma membrane of human lymphocytes were studied based on 86Rb and 45Ca fluxes. Net Ca-uptake increases K(Rb)-permeability (Gardos-effect) and the membrane potential increases due to the subsequent K-efflux, enabling further Ca-uptake. The possible role of the above effects during lymphocyte stimulation is discussed. (L.E.)

  2. Regulation of the sodium/potassium/chloride cotransporter by calcium and cyclic AMP in cultured vascular smooth muscle cells

    Higgins, B.L.; Smith, L.; Smith, J.B.

    1987-05-01

    The activity of the Na/K/Cl cotransporter in smooth muscle cells cultured from rat aorta was assayed by measuring the initial rate of furosemide-inhibitable /sup 86/Rb influx or efflux. Five uM furosemide or 0.2 uM bumetanide inhibited influx by 50%. Furosemide-inhibitable /sup 86/Rb influx depended on the presence of all 3 ions in the external medium. The dependence on Na and K was hyperbolic with apparent Km values of 45 and 5 mM, respectively. The dependence on Cl was sigmoidal. Assuming a stoichiometry of 1:1:2 for Na:K:Cl, a Km for Cl of 60 mM was obtained from a Hofstee plot of the data. Rapidly growing cells had 3 fold higher cotransport activity than quiescent cells. Angiotensin II (ANG) stimulated furosemide-inhibitable /sup 86/Rb efflux by 2 fold. An ANG receptor antagonist prevented ANG from increasing cotransport activity. Two calcium ionophores, A23187 and ionomycin, increased cotransport activity by 2 fold. Phorbol myristate acetate had no effect on cotransport activity. Isoproterenol, dibutyryl cyclic AMP, cholera toxin, or methylisobutylxanthine inhibited furosemide-sensitive /sup 86/Rb influx by 35 to 50%. From these findings they conclude that increasing cytoplasmic free calcium stimulates cotransport activity, whereas increasing cellular cyclic AMP inhibits the cotransporter.

  3. Genetic analysis of inheritance of rates of Na+, K+-cotransport, calcium concentration in erythrocytes, and blood pressure of F2 hybrids of spontaneously hypertensive and normotensive rats

    Inheritance of the rates of Na+, K+-cotransport, measured as the furosemide-sensitive component of the 86Rb inflow, the 45Ca concentration in the erythrocytes in the presence of orthovanadate, and BP were analyzed in second generation hybrids of spontaneously hypertensive Kyoto-Wistar rats and normotensive Kyoto-Wistar rats of the control line

  4. ATP-sensitive K+ channels that are blocked by hypoglycemia-inducing sulfonylureas in insulin-secreting cells are activated by galanin, a hyperglycemia-inducing hormone

    The action of the hyperglycemia-inducing hormone galanin, a 29-amino acid peptide names from its N-terminal glycine and C-terminal amidated alanine, was studied in rat insulinoma (RINm5F) cells using electrophysiological and 86Rb+ flux techniques. Galanin hyperpolarizes and reduces spontaneous electrical activity by activating a population of APT-sensitive K+ channels with a single-channel conductance of 30 pS (at -60 mV). Galanin-induced hyperpolarization and reduction of spike activity are reversed by the hypoglycemia-inducing sulfonylurea glibenclamine. Glibenclamide blocks the galanin-activated ATP-sensitive K+ channel. 86Rb+ efflux from insulinoma cells is stimulated by galanin in a dose-dependent manner. The half-maximum value of activation is found at 1.6 nM. Galanin-induced 86Rb+ efflux is abolished by glibenclamide. The half-maximum value of inhibition is found at 0.3 nM, which is close to the half-maximum value of inhibition of the ATP-dependent K+ channel reported earlier. 86Rb+ efflux studies confirm the electrophysiological demonstration that galanin activates and ATP-dependent K+ channel

  5. ATP-sensitive K/sup +/ channels that are blocked by hypoglycemia-inducing sulfonylureas in insulin-secreting cells are activated by galanin, a hyperglycemia-inducing hormone

    de Weille, J.; Schmid-Antomarchi, H.; Fosset, M.; Lazdunski, M.

    1988-02-01

    The action of the hyperglycemia-inducing hormone galanin, a 29-amino acid peptide names from its N-terminal glycine and C-terminal amidated alanine, was studied in rat insulinoma (RINm5F) cells using electrophysiological and /sup 86/Rb/sup +/ flux techniques. Galanin hyperpolarizes and reduces spontaneous electrical activity by activating a population of APT-sensitive K/sup +/ channels with a single-channel conductance of 30 pS (at -60 mV). Galanin-induced hyperpolarization and reduction of spike activity are reversed by the hypoglycemia-inducing sulfonylurea glibenclamine. Glibenclamide blocks the galanin-activated ATP-sensitive K/sup +/ channel. /sup 86/Rb/sup +/ efflux from insulinoma cells is stimulated by galanin in a dose-dependent manner. The half-maximum value of activation is found at 1.6 nM. Galanin-induced /sup 86/Rb/sup +/ efflux is abolished by glibenclamide. The half-maximum value of inhibition is found at 0.3 nM, which is close to the half-maximum value of inhibition of the ATP-dependent K/sup +/ channel reported earlier. /sup 86/Rb/sup +/ efflux studies confirm the electrophysiological demonstration that galanin activates and ATP-dependent K/sup +/ channel.

  6. Effect of angiotensin II, ATP, and ionophore A23187 on potassium efflux in adrenal glomerulosa cells

    Angiotensin II stimulus on perifused bovine adrenal glomerulosa cells elicited an increase in 86Rb efflux from cells previously equilibrated with the radioisotope. When 45Ca fluxes were measured under similar conditions, it was observed that Ca and Rb effluxes occurred within the first 30 s of the addition of the hormone and were independent of the presence of external Ca. The 86Rb efflux due to angiotensin II was inhibited by quinine and apamin. The hypothesis that the angiotensin II response is a consequence of an increase in the K permeability of the glomerulosa cell membrane triggered by an increase in cytosolic Ca is supported by the finding that the divalent cation ionophore A23187 also initiated 86Rb or K loss (as measured by an external K electrode). This increased K conductance was also seen with 10(-4) M ATP. Quinine and apamin greatly reduced the effect of ATP or A23187 on 86Rb or K release in adrenal glomerulosa cells. The results suggest that Ca-dependent K channels or carriers are present in the membranes of bovine adrenal glomerulosa cells and are sensitive to hormonal stimulus

  7. Volume regulation by human lymphocytes. Role of calcium

    Human peripheral blood lymphocytes regulate their volumes in hypotonic solutions. In hypotonic media in which Na+ is the predominant cation, an initial swelling phase is followed by a regulatory volume decrease (RVD) associated with a net loss of cellular K+. In media in which K+ is the predominant cation, the rapid initial swelling is followed by a slower second swelling phase. 86Rb+ fluxes increased during RVD and returned to normal when the original volume was approximately regained. Effects similar to those induced by hypotonic stress could also be produced by raising the intracellular Ca++ level. In isotonic, Ca++-containing media cells were found to shrink upon addition of the Ca++ ionophore A23187 in K+-free media, but to swell in K+-rich media. Exposure to Ca++ plus A23187 also increased 86Rb+ fluxes. Quinine (75 microM), an inhibitor of the Ca++-activated K+ pathway in other systems blocked RVD, the associated K+ loss, and the increase in 86Rb+ efflux. Quinine also inhibited the volume changes and the increased 86Rb fluxes induced by Ca++ plus ionophore. The calmodulin inhibitors trifluoperazine, pimozide and chlorpromazine blocked RVD as well as Ca++ plus A23187-induced volume changes. Trifluoperazine also prevented the increase in 86Rb+ fluxes and K+ loss induced by hypotonicity. Chlorpromazine sulfoxide, a relatively ineffective calmodulin antagonist, was considerably less potent as an inhibitor of RVD than chlorpromazine. It is suggested than an elevation in cytoplasmic [Ca++], triggered by cell swelling, increases the plasma membrane permeability to K+, the ensuing increased efflux of K+, associated anions, and osmotically obliged water, leading to cell shrinking

  8. Extracellular ATP4- promotes cation fluxes in the J774 mouse macrophage cell line

    Extracellular ATP stimulates transmembrane ion fluxes in the mouse macrophage cell line J774. In the presence of Mg2+, nonhydrolyzable ATP analogs and other purine and pyrimidine nucleotides do not elicit this response, suggesting the presence of a specific receptor for ATP on the macrophage plasma membrane. One candidate for such a receptor is the ecto-ATPase expressed on these cells. We, therefore, investigated the role of this enzyme in ATP-induced 86Rb+ efflux in J774 cells. The ecto-ATPase had a broad nucleotide specificity and did not hydrolyze extracellular ATP in the absence of divalent cations. 86Rb+ efflux was not blocked by inhibition of the ecto-ATPase and did not require Ca2+ or Mg2+. In fact, ATP-stimulated 86Rb+ efflux was inhibited by Mg2+ and correlated with the availability of ATP4- in the medium. In the absence of divalent cations, the slowly hydrolyzable ATP analogs adenosine 5'-(beta, gamma-imido)triphosphate (AMP-PNP) and adenosine 5'-O-(3-thio)triphosphate (ATP-gamma-S) also stimulated 86Rb+ efflux, albeit at higher concentrations than that required for ATP4-. Exposure of J774 cells to 10 mM ATP for 45 min caused death of 95% of cells. By this means we selected variant J774 cells that did not exhibit 86Rb+ efflux in the presence of extracellular ATP but retained ecto-ATPase activity. These results show that the ecto-ATPase of J774 cells does not mediate the effects of ATP on these cells; that ATP4- and not MgATP2- promotes 86Rb+ efflux from these cells; and that hydrolysis of ATP is not required to effect this change in membrane permeability. These findings suggest that J774 cells possess a plasma membrane receptor which binds ATP4-, AMP-PNP, and ATP-gamma-S, and that the ecto-ATPase limits the effects of ATP on these cells by hydrolyzing Mg-ATP2-

  9. Extracellular ATP4- promotes cation fluxes in the J774 mouse macrophage cell line

    Steinberg, T.H.; Silverstein, S.C.

    1987-03-05

    Extracellular ATP stimulates transmembrane ion fluxes in the mouse macrophage cell line J774. In the presence of Mg2+, nonhydrolyzable ATP analogs and other purine and pyrimidine nucleotides do not elicit this response, suggesting the presence of a specific receptor for ATP on the macrophage plasma membrane. One candidate for such a receptor is the ecto-ATPase expressed on these cells. We, therefore, investigated the role of this enzyme in ATP-induced /sup 86/Rb+ efflux in J774 cells. The ecto-ATPase had a broad nucleotide specificity and did not hydrolyze extracellular ATP in the absence of divalent cations. /sup 86/Rb+ efflux was not blocked by inhibition of the ecto-ATPase and did not require Ca2+ or Mg2+. In fact, ATP-stimulated /sup 86/Rb+ efflux was inhibited by Mg2+ and correlated with the availability of ATP4- in the medium. In the absence of divalent cations, the slowly hydrolyzable ATP analogs adenosine 5'-(beta, gamma-imido)triphosphate (AMP-PNP) and adenosine 5'-O-(3-thio)triphosphate (ATP-gamma-S) also stimulated /sup 86/Rb+ efflux, albeit at higher concentrations than that required for ATP4-. Exposure of J774 cells to 10 mM ATP for 45 min caused death of 95% of cells. By this means we selected variant J774 cells that did not exhibit /sup 86/Rb+ efflux in the presence of extracellular ATP but retained ecto-ATPase activity. These results show that the ecto-ATPase of J774 cells does not mediate the effects of ATP on these cells; that ATP4- and not MgATP2- promotes /sup 86/Rb+ efflux from these cells; and that hydrolysis of ATP is not required to effect this change in membrane permeability. These findings suggest that J774 cells possess a plasma membrane receptor which binds ATP4-, AMP-PNP, and ATP-gamma-S, and that the ecto-ATPase limits the effects of ATP on these cells by hydrolyzing Mg-ATP2-.

  10. K+ transport across the lamprey erythrocyte membrane: characteristics of a Ba(2+)- and amiloride-sensitive pathway.

    Kirk, K

    1991-09-01

    The characteristics of K+ transport in erythrocytes from the river lamprey (Lampetra fluviatilis) were investigated using standard radioisotope flux techniques. The cells were shown to have a ouabain-sensitive transport pathway that carried 43K+ and 86Rb+ into the cell at similar rates. Most of the ouabain-resistant 43K+ and 86Rb+ influx was via a pathway that was insensitive to cotransport inhibitors and to the replacement of extracellular Cl- or Na+. This pathway showed a strong selectivity for 43K+ over 86Rb+. It was inhibited fully by Ba2+ (I50 approximately 2.8 mumol l-1), amiloride (I50 approximately 150 mumol l-1) and ethylisopropylamiloride (I50 approximately 3.3 mumol l-1) and less effectively by quinine and by the tetraethylammonium ion. Inhibition by Ba2+ took full effect within a few minutes whereas the full inhibitory effect of amiloride took more than 1 h to develop. Experiments with the membrane potential probe [14C]tetraphenylphosphonium ion gave results consistent with the lamprey erythrocyte membrane having a Ba(2+)-sensitive K+ conductance that was significantly greater than the membrane Na+ conductance and which gave rise to a marked dependence of the membrane potential on the extracellular K+ concentration. The rate constants for Ba(2+)-sensitive 43K+ and 86Rb+ influx decreased (proportionally) with increasing extracellular K+ concentration in a manner that was consistent with the transport being via a conductive pathway. The decrease was attributed to a depolarisation of the membrane (in response to the increasing extracellular K+ concentration) and a consequent decrease in the driving force for the conductive movement of 43K+ and 86Rb+ into the cells. Ba(2+)-sensitive 86Rb+ influx increased significantly with decreasing cell volume and with increasing intracellular pH (at a constant extracellular pH) but increased only slightly with increasing extracellular pH. The pathway operated normally in the complete absence of extracellular Ca2+ but

  11. Vascular effects of photodynamic therapy in an intraocular retinoblastoma-like tumour

    Results from experimental tumours suggest that the mechanism of action of photodynamic therapy (PDT) involves both a direct killing of tumour cells, and a secondary effect resulting from vascular damage. We have investigated the possible vascular changes induced by PDT in an intraocular retinoblastoma-like rat tumour model using the 86RbCl extraction procedure. Light irradiation (90 J/cm2; 633 nm; 30 min) of intraocular tumours 24 h after an intraperitoneal injection of 5 mg/kg Photofrin II produced an increase in the tumour uptake of 86RbCl during the treatment period. However, 24 h later these values had decreased to 25% of that normally found in control animals. These effects were observed in both the tumour material and associated normal eye tissue, but not in PDT treated normal eyes without tumours. The results confirm that the vasculature of this eye tumour model is a target for some of the PDT effects. (orig.)

  12. Evidence for differential action of indoleacetic acid upon ion fluxes in single cells of Petroselinum sativum.

    Bentrup, F W; Pfrüner, H; Wagner, G

    1973-12-01

    The apparent influx of (36)Cl(-) and (86)Rb(+)/K(+) into cells from the higher plant Petroselinum sativum has been measured during the presence and absence in the culture medium of indolacetic acid (IAA) which is an essential auxin of these cells. While 10(-5) M IAA did not significantly affect the influx of (86)Rb(+)/K(+), it substantially reduced that of (36)Cl(-), i.e. by a factor 0.25 within 30 min. This differential action of IAA, which holds for a reasonable range of external pH, is assumed to bear on current hypotheses that the primary events of auxin action involve plasmalemma functions. PMID:24474466

  13. Regulation of ATP-sensitive K+ channels in insulinoma cells: Activation by somatostatin and protein kinase C and the role of cAMP

    The actions of somatostatin and of the phorbol ester 4β-phorbol 12-myristate 13-acetate (PMA) were studied in rat insulinoma (RINm5F) cells by electrophysiological and 86Rb+ flux techniques. Both PMA and somatostatin hyperpolarize insulinoma cells by activating ATP-sensitive K+ channels. The presence of intracellular GTP is required for the somatostatin effects. PMA- and somatostatin-induced hyperpolarization and channel activity are inhibited by the sulfonylurea glibenclamide. Glibenclamide-sensitive 86Rb+ efflux from insulinoma cells is stimulated by somatostatin in a dose-dependent manner (half maximal effect at 0.7 nM) and abolished by pertussis toxin pretreatment. Mutual roles of a GTP-binding protein, of protein kinase C, and of cAMP in the regulation of ATP-sensitive K+ channels are discussed

  14. Nuclear physics techniques for determination of rocks age

    The low background nuclear physics techniques were used for measure age geologic samples of micas (biotite, lepidolite, muscovite, phlogopite) by means of detection a gamma radiation from radioisotopes. The nuclear reactions 87Sr(gamma,gamma)87mSr, 87Rb(gamma,n)86Rb and 85Rb(gamma,n)84Rb was used. Application of a braking radiation of the powerful accelerator of electrons has allowed simultaneously to measure an element composition of samples

  15. Protein tyrosine phosphorylation is involved in osmoregulation of ionic conductances

    Tilly, Bernard; Berghe, Nina; Tertoolen, L G; Edixhoven, Marcel; de Jonge, Hugo

    1993-01-01

    textabstractUsing the human Intestine 407 cell line as a model, we investigated a possible role for tyrosine kinase(s) in regulating the ion efflux pathways induced by hyposmotic stimulation (regulatory volume decrease, RVD). Pretreatment of 125I(-)-and 86Rb(+)-loaded cells with the phosphotyrosine phosphatase inhibitor sodium orthovanadate (200 microM) potentiated isotope efflux triggered by mild hypotonicity (10-20%) but did not further increase the efflux in response to more vigorous osmot...

  16. Genetic analysis of inheritance of rates of Na/sup +/, K/sup +/-cotransport, calcium concentration in erythrocytes, and blood pressure of F/sub 2/ hybrids of spontaneously hypertensive and normotensive rats

    Kotelevtsev, Yu.V.; Orlov, S.N.; Pokudin, N.I.; Agnaev, V.M.; Postnov, Yu.V.

    1987-09-01

    Inheritance of the rates of Na/sup +/, K/sup +/-cotransport, measured as the furosemide-sensitive component of the /sup 86/Rb inflow, the /sup 4//sub 5/Ca concentration in the erythrocytes in the presence of orthovanadate, and BP were analyzed in second generation hybrids of spontaneously hypertensive Kyoto-Wistar rats and normotensive Kyoto-Wistar rats of the control line.

  17. A 28,000 mol. wt toxin from Bacillus thuringiensis israelensis induces cation transport in rat muscle cultures.

    Cahan, R; Shainberg, A; Pechatnikov, I; Nitzan, Y

    1995-07-01

    The mechanism by which the Bacillus thuringiensis israelensis (Bti) 28,000 mol. wt toxin exerts its effect on mature muscle cultures was examined. The toxin inhibited Na+/K(+)-ATPase activity as revealed by 86Rb influx. A 50% inhibition of Na+/K(+)-ATPase activity was obtained with 0.2 microgram/ml of the toxin. The inhibition was time and dose dependent, and it was reversible with low doses of the toxin (up to 0.2 microgram/ml. A considerable release of 86Rb was obtained by doses greater than 0.2 microgram/ml. The 86Rb release was also time and dose dependent. This effect is probably non-specific, since 45Ca influx is also accelerated by toxin-treated cultures. Pre-incubation of the toxin with phosphotidylserine (PS) antagonized the toxin. It is concluded that the toxin is a hydrophobic protein which interacts with the membrane. In low doses this interaction reduces the activity of the sodium pump and in high doses it causes non-specific permeability of the sarcolemma. PMID:8588218

  18. Volume regulatory potassium transport in rabbit and human sickle erythrocytes in vitro

    One approach to the therapy of sickle cell anemia is to decrease the hemoglobin concentration by inducing a slight swelling of the cell to retard the rate of hemoglobin polymerization. We found that a prolonged incubation of rabbit or human SS red cell in hypotonic medium caused an inactivation of the inactivation of swelling-stimulated potassium transport. The inactivation may have important practical consequences for the therapy of sickle cell anemia. Large cytoskeleton-free vesicles were prepared in order to study the possible role of the spectrin-actin membrane skeleton in the swelling-stimulated and N-ethylmaleimide (NEM)-stimulated transport. NEM pretreatment stimulated 86Rb efflux in vesicles by a factor of 2.4 + 0.55 (mean ± S.D.). The NEM effect on 86Rb efflux was specific in that the 22Na efflux into a Na medium was not stimulated but actually inhibited. The 86Rb efflux from the vesicles was not stimulated by hypotonic media. This finding is consistent with a role of the membrane skeleton in the detection and/or transduction of the signal by which cell swelling activates the transport

  19. Furosemide-induced airway relaxation in guinea pigs: relation to Na-K-2Cl cotransporter function.

    Lavallee, S L; Iwamoto, L M; Claybaugh, J R; Dressel, M V; Sato, A K; Nakamura, K T

    1997-07-01

    This study tested the hypothesis that airway relaxation to furosemide is mediated via the Na-K-2Cl cotransporter. If this mechanism exists in airway smooth muscle like in vascular smooth muscle, changes in airway relaxation should be associated with changes in Na-K-2Cl cotransporter function, and both should be substrate dependent. Tracheal rings from newborn guinea pigs were bathed in standard (STD) or varying low Cl- concentration ([Cl-]) N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES). Isometric relaxation to 300 microM furosemide or 10(-8) to 10(-5) M salbutamol was measured. Airway segments were incubated with rubidium-86 (86Rb) in STD or varying low [Cl-] HEPES, with and without 300 microM furosemide or 25 microM salbutamol. Furosemide was unable to reduce 86Rb uptake at 10 mM [Cl-], although relaxation was still observed in 10 mM [Cl-]. Salbutamol did not affect 86Rb uptake. This study demonstrated that there is a furosemide-sensitive Na-K-2Cl cotransporter in newborn guinea pig trachea. However, the effect of furosemide on cotransporter function did not always directly correspond to differences in relaxation, suggesting that the Na-K-2Cl cotransporter may play a major, but not exclusive, role in furosemide-induced airway relaxation. PMID:9252558

  20. A functional assay to measure postsynaptic gamma-aminobutyric acidB responses in cultured spinal cord neurons: Heterologous regulation of the same K+ channel

    Kamatchi, G.L.; Ticku, M.K. (Univ. of Texas Health Science Center, San Antonio (USA))

    1991-02-01

    The stimulation of postsynaptic gamma-aminobutyric acid (GABA)B receptors leads to slow inhibitory postsynaptic potentials due to the influx of K(+)-ions. This was studied biochemically, in vitro in mammalian cultured spinal cord neurons by using 86Rb as a substitute for K+. (-)-Baclofen, a GABAB receptor agonist, produced a concentration-dependent increase in the 86Rb-influx. This effect was stereospecific and blocked by GABAB receptor antagonists like CGP 35 348 (3-aminopropyl-diethoxymethyl-phosphonic acid) and phaclofen. Apart from the GABAB receptors, both adenosine via adenosine1 receptors and 5-hydroxytryptamine (5-HT) via 5-HT1 alpha agonists also increased the 86Rb-influx. These agonists failed to show any additivity between them when they were combined in their maximal concentration. In addition, their effect was antagonized specifically by their respective antagonists without influencing the others. These findings suggest the presence of GABAB, adenosine1 and 5-HT1 alpha receptors in the cultured spinal cord neurons, which exhibit a heterologous regulation of the same K(+)-channel. The effect of these agonists were antagonized by phorbol 12,13-didecanoate, an activator of protein kinase C, and pretreatment with pertussis toxin. This suggests that these agonists by acting on their own receptors converge on the same K(+)-channel through the Gi/Go proteins. In summary, we have developed a biochemical functional assay for studying and characterizing GABAB synaptic pharmacology in vitro, using spinal cord neurons.

  1. A functional assay to measure postsynaptic gamma-aminobutyric acidB responses in cultured spinal cord neurons: Heterologous regulation of the same K+ channel

    The stimulation of postsynaptic gamma-aminobutyric acid (GABA)B receptors leads to slow inhibitory postsynaptic potentials due to the influx of K(+)-ions. This was studied biochemically, in vitro in mammalian cultured spinal cord neurons by using 86Rb as a substitute for K+. (-)-Baclofen, a GABAB receptor agonist, produced a concentration-dependent increase in the 86Rb-influx. This effect was stereospecific and blocked by GABAB receptor antagonists like CGP 35 348 (3-aminopropyl-diethoxymethyl-phosphonic acid) and phaclofen. Apart from the GABAB receptors, both adenosine via adenosine1 receptors and 5-hydroxytryptamine (5-HT) via 5-HT1 alpha agonists also increased the 86Rb-influx. These agonists failed to show any additivity between them when they were combined in their maximal concentration. In addition, their effect was antagonized specifically by their respective antagonists without influencing the others. These findings suggest the presence of GABAB, adenosine1 and 5-HT1 alpha receptors in the cultured spinal cord neurons, which exhibit a heterologous regulation of the same K(+)-channel. The effect of these agonists were antagonized by phorbol 12,13-didecanoate, an activator of protein kinase C, and pretreatment with pertussis toxin. This suggests that these agonists by acting on their own receptors converge on the same K(+)-channel through the Gi/Go proteins. In summary, we have developed a biochemical functional assay for studying and characterizing GABAB synaptic pharmacology in vitro, using spinal cord neurons

  2. K-Cl transport systems in rabbit renal basolateral membrane vesicles

    The transport pathways for chloride in basolateral membrane vesicles from the rabbit renal cortex were investigated. 36Cl uptake was stimulated by the presence of potassium in the uptake media compared with sodium of N-methyl-D-glucamine. In addition, potassium (86Rb) uptake was stimulated more by chloride than by nitrate or gluconate. Neither of these processes was further stimulated by potassium gradients plus valinomycin, suggesting the presence of an electrically neutral K-Cl cotransport system. A magnesium-induced chloride conductance was also found in the basolateral membrane vesicles. In the absence of magnesium, the chloride conductance was low; valinomycin and an inwardly directed potassium gradient did not stimulated 36Cl uptake, anthracene-9-carboxylic acid did not inhibit 36Cl uptake, and valinomycin did not stimulated chloride-dependent 86Rb uptake. However, in the presence of 1 mM magnesium, opposite results were obtained; valinomycin and an inwardly directed potassium gradient stimulated 36Cl uptake, anthracene-9-carboxylic acid inhibited 36Cl uptake, and valinomycin stimulated chloride-dependent 86Rb uptake. Therefore, an electrically neutral K-Cl cotransport and magnesium-induced chloride conductance were found in renal cortial basolateral membrane vesicles prepared from the rabbit renal cortex

  3. Cation transport and membrane potential properties of primary astroglial cultures from neonatal rat brains

    This paper describes K+ and Na+ content and transport in primary monolayer cultures from dissociated newborn rat brains, considered to consist predominantly of astroglial cells. Net changes in cation content after addition of ouabain, and steady state fluxes using 86Rb+ as a marker for K+ and 22Na+ as a marker for Na+, were measured. The results found indicate that the cells maintained a conventional pattern of cation homeostasis with net efflux of K+ being balanced by its active uptake and net uptake of Na+ balanced by active extrusion mediated by a ouabain sensitive (Na + K) pump. These processes maintained internal measured K+:Na+ ratios of 12-25:1. The cells were normally flat but addition of DBcAMP caused them to round up and form numerous processes, an appearance resembling that of astroglial cells in vivo. DBcAMP treatment also reduced the steady state levels of K+ measured with 86Rb+ by 15-30%, and had no effect on initial rates of 86Rb+ and 22Na+ uptake. (Auth.)

  4. Early effects of aldosterone on Na-K pump in rat cortical collecting tubules

    Sustained exposure to aldosterone (Aldo) increases the abundance and activity of the Na-K pump in cortical collecting tubules (CCT). However, the onset and mechanism of the early interaction of Aldo with the CCT pump, especially in adrenal-intact animals, are unclear. We evaluated the short-term effects of the hormone on Na-K-adenosinetriphosphatase (ATPase) activity and on ouabain-sensitive 86Rb uptake, a measure of the transporting rate of the pump, in microdissected CCT from adrenal-intact rats. Incubation with Aldo (10(-8) M, 2 h) had no effect on Na-K-ATPase activity (Vmax), whereas it produced at least a twofold increase in 86Rb uptake. This effect was generated by physiological concentrations of the hormone (threshold 10(-10) M; apparent K1/2 approximately 10(-9) M), after a short lag of less than or equal to 30 min. Incubation with Aldo in the presence of amiloride or nystatin or in a Na-free medium (choline chloride) did not prevent the enhanced 86Rb uptake seen after Aldo alone; possible interpretations of these observations are discussed. We conclude that Aldo produces a rapid stimulation of pump function in CCT that precedes its induction of new pump synthesis; the physiological significance of this effect is suggested by its occurrence in tubules from adrenal-intact animals within the time frame and concentration range of the hormone's effects on electrolyte transport

  5. Oligosaccharide composition of the neurotoxin responsive Na+ channel and the requirement of sialic acid for activity

    The neurotoxin responsive Na+ channel was purified to homogeneity in an 18% yield from a clonal cell line of mouse neuroblastoma, N-18, metabolically labeled with L-[3H]fucose. The Na+ channel, a glycoprotein, M/sub r/=200,000 (gradient 7-14% PAGE) was digested with Pronase and the glycopeptides were characterized by serial lectin affinity chromatography. greater than 90% of the oligosaccharides contained sialic acid and 18% were biantennary, 39% were triantennary and 30% tetraantennary. The glycoprotein was reconstituted into artificial phospholipid vesicles and 86Rb flux was stimulated (65%) by 200 μM veratridine and 1.2 μg of scorpion venom and was inhibited (95%) by 5 μM tetrodotoxin. The requirement of sialic acid for Na+ channel activity was demonstrated since neuraminidase (0.01 U) treatment of the reconstituted glycoprotein eliminated the response of 86Rb flux to the stimulating neurotoxins. In other experiments, treatment of N-18 cells with 10 μM swainsonine, an inhibitor of glycoprotein processing, altered the oligosaccharide composition of the Na+ channel. When the abnormally glycosylated Na+ channel was reconstituted into artificial phospholipid vesicles, 86Rb flux in response to neurotoxins was impaired. Thus, glycosylation of the polypeptide with oligosaccharides of specific composition and structure is essential for expression of the biological activity of the neurotoxin responsive Na+ channel

  6. Effect of dopamine and amine-oxidase inhibitors in experimental myocardial infarction in rats

    Cardiac necrosis was induced in rats by isoproterenol (ISO) (85 mg/kg, sc) administered daily for 2 days. The average degree of cardiac necrosis was significantly less in animals pretreated for 4 days before and 2 days during ISO administration with either nialamide (30 mg/kg) or phenelzine (25 mg/kg). Dopamine (100 μg/kg) also produced salutory effects in cardiac necrosis in ISO injected group. The extent of damage was further reduced if nialamide and dopamine were given together for 4 days before and 3 days during ISO administration. 86Rb uptake by the myocardium was significantly lower (at. 52.8 +- 7%) in ISO injected rats. When the rats were pretreated with nialamide or phenelzine, the 86Rb uptake was significantly increased to 68.7 +- 3.2 and 71.5 +- 5.5 in comparison to ISO injected group. In dopamine pretreated group, the 86Rb uptake was increased to 62.5 +- 3.5 but maximum increase (82.5 +- 4.2) occurred in rats pretreated with dopamine + nialamide. Thus a combination of dopamine with nialamide may offer a promising therapeutic approach. (author)

  7. Stimulus-secretion coupling of arginine-induced insulin release: comparison with lysine-induced insulin secretion

    L-Lysine, like-L-arginine, L-ornithine, or L-homoarginine, accumulated in rat pancreatic islets and stimulated 86Rb efflux, 45Ca uptake and efflux, and insulin release in islets exposed to D-glucose (7.0 mM). The effect of L-lysine differed from that of the other cationic amino acids by such features as the absence of a threshold concentration for stimulation of insulin release, a much lesser sensitivity of the secretory response to intracellular acidification, and the stimulation of 86Rb net uptake over 60 min of incubation. This coincided with the fact that even in the absence of another exogenous nutrient, L-lysine was well oxidized, augmented NH4+ production, increased both the ATP content and ATP/ADP ratio, caused a time-related decrease in 86Rb fractional outflow, and provoked either a transient (10 mM L-lysine) or sustained (20 mM L-lysine) stimulation of insulin secretion. It is proposed, therefore, that the functional response of the pancreatic B-cell to L-lysine involves not only a biophysical mechanism similar to that responsible for the insulinotropic action of L-homoarginine, but also a significant, albeit modest, metabolic component, which reflects the capacity of L-lysine to act as a fuel in islet cells

  8. The mechanism of patulin's cytotoxicity and the antioxidant activity of indole tetramic acids

    Riley, R.T.; Showker, J.L. (Toxicology and Mycotoxins Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Athens, GA (USA))

    1991-06-01

    In LLC-PK1 cells exposed to patulin (50 microM), lipid peroxidation, abrupt calcium influx, extensive blebbing, and total LDH release appeared to be serially connected events with each representing a step in the loss of structural integrity of the plasma membrane. The aforementioned patulin-induced events were prevented by concurrent incubation with butylated hydroxytoluene, deferoxamine, and cyclopiazonic acid, a fungal metabolite. Patulin also caused depletion of nonprotein sulfhydryls, increased 86Rb+ efflux, dome collapse, and eventually the loss of cell viability. These events were not prevented by antioxidants, results consistent with the hypothesis that they were also serially connected but occurring parallel to those previously mentioned. The earliest events observed in patulin-treated cells were the decrease in nonprotein sulfhydryls and increase in 86Rb+ efflux (5 min) which occurred before statistically significant alterations in protein-bound sulfhydryls. The increased potassium efflux (86Rb+ efflux) occurred via a pathway distinct from BaCl2, quinine, or tetraethylammonium sensitive potassium channels. This is the first published report of the antioxidant activity of indole tetramic acids (cyclopiazonic acid and cyclopiazonic acid imine). The protective effect of tetramic acids in LLC-PK1 cells was restricted to indole tetramic acids, and their prevention of lipid peroxidation did not involve iron chelation. The results of this study demonstrate that cyclopiazonic acid is a potent inhibitor of azide-insensitive, ATP-dependent, a23187-sensitive calcium uptake by the lysate of LLC-PK1 cells. This result is consistent with the hypothesis that the endoplasmic reticulum calcium transport ATPase is a sensitive target for cyclopiazonic acid in LLC-PK1 cells.

  9. Mechanisms behind the relaxing effect of furosemide on the isolated rabbit ear artery

    The effect of furosemide on isometric contration and 86Rb uptake were studied in the isolated rabbit central ear artery (CEA). A concentration-dependent relaxing effect of furosemide (0.06 mM-1.0 mM) was found in vessel segments with intact endothelium. The maximal relaxation was 28.6±3.9% (10). The effect was not diminished in segments deprived of endothelium, and removal of endothelium itself caused no change of the force development to electrical field stimualtion. The relaxing effect was time-dependent and stimulation-dependent and was not significantly affected by membrane depolarization induced by increasing external [K+] from 10 to 120 mM. The 86Rb uptake was inhibited by both furosemide and ouabain (8.0±0.5(8) and 5.3±0.5(8) versus 12.8±0.9(16) nmol (K+)x mm-1x(10 min.)-1 in the furosemide (1.0 mM), ouabain (1.0 mM) and control groups, respectively) without interaction between the two drugs. The 86Rb uptake was not further inhibited by increasing the furosemide concentration from 0.12 mM to 1.0 mM. Our results suggest: firstly, the direct relaxing effect of furosemide on isolated vessel segments in endothelium-independent and secondly, the inhibition of the Na+-K+-Cl- cotransport and a possible consequent hyperpolarization of the membrane is unlikely to be the sole mechanism responsible for the vasorelaxant effect of furosemide. The demonstrated direct effect on vascular tone may be of clinical importance in situations with very high plasma concentrations of the drug or very low concentrations of serum albumin. (aluthor)

  10. Regulation of membrane transport and metabolism in the HT29 human colonic adenocarcinoma cell line

    The effects of insulin on glucose transport and metabolism were examined in cultured HT29 human colonic adenocarcinoma cells. The presence of glucose transporters was verified by D-glucose displaceable [3H] cytochalasin B binding. Moreover, two classes of insulin binding sites were detected in radioligand binding experiments. Despite the presence of both glucose transporters and insulin receptors, insulin failed to stimulate glucose transport. However, insulin was found to activate glycolysis. These findings suggest that insulin directly influences substrate utilization through the glycolytic pathway in HT29 cells without activating the glucose transport pathway. A Na+/K+/Cl- cotransport pathway was also detected in HT29 cells using 86Rb+ as a K+ congener. The identity of this pathway as a Na+/K+/Cl- cotransporter has been deduced from the following findings: (1) 86Rb+ influx was inhibited by loop diuretics, (2) 86Rb+ influx ceased in the absence of any one of the transported ions, and (3) cotransport exhibited a stoichiometry approaching 1Na+:1K+:2Cl-. Na+/K+/Cl- cotransport was found to be exquisitely sensitive to cellular ATP and cyclic AMP levels. These results suggest that HT29 cells contain a Na+/K+/Cl- cotransport pathway that can be regulated by the second messenger cyclic AMP and is highly sensitive to the metabolic state of the cell. The involvement of protein kinase C in the regulation of Na+/K+/Cl- cotransport was also investigated. Phorbol 12-myristate 13-acetate (PMA), which stimulated protein kinase C activity, produced a transient increase in cotransport followed by a near abolition of cotransport by 2 h

  11. Intracellular mediators of Na+-K+ pump activity in guinea pig pancreatic acinar cells

    The involvement of Ca2+ and cyclic nucleotides in neurohormonal regulation of Na+-K+-ATPase (Na+-K+ pump) activity in guinea pig pancreatic acinar cells was investigated. Changes in Na+-K+ pump activity elicited by secretagogues were assessed by [3H]ouabain binding and by ouabain-sensitive 86Rb+ uptake. Carbachol (CCh) and cholecystokinin octapeptide (CCK-8) each stimulated both ouabain-sensitive 86Rb+ uptake and equilibrium binding of [3H]ouabain by approximately 60%. Secretin increased both indicators of Na+-K+ pump activity by approximately 40% as did forskolin, 8-bromo- and dibutyryl cAMP, theophylline, and isobutylmethylxanthine. Incubation of acinar cells in Ca2+-free HEPES-buffered Ringer (HR) with 0.5 mM EGTA reduced the stimulatory effects of CCh and CCK-8 by up to 90% but caused only a small reduction in the effects of secretin, forskolin, and cAMP analogues. In addition, CCh, CCK-8, secretin, and forskolin each stimulated ouabain-insensitive 86Rb+ uptake by acinar cells. The increase elicited by CCh and CCK-8 was greatly reduced in the absence of extracellular Ca2+, while that caused by the latter two agents was not substantially altered. The effects of secretagogues on free Ca2+ levels in pancreatic acinar cells also were investigated with quin-2, a fluorescent Ca2+ chelator. Basal intracellular Ca2+ concentration ([Ca2+]i) was 161 nM in resting cells and increased to 713 and 803 nM within 15 s after addition of 100 microM CCh or 10 nM CCK-8, respectively

  12. Early events elicited by bombesin and structurally related peptides in quiescent Swiss 3T3 cells. II. Changes in Na+ and Ca2+ fluxes, Na+/K+ pump activity, and intracellular pH

    The amphibian tetradecapeptide, bombesin, and structurally related peptides caused a marked increase in ouabain-sensitive 86Rb+ uptake (a measure of Na+/K+ pump activity) in quiescent Swiss 3T3 cells. This effect occurred within seconds after the addition of the peptide and appeared to be mediated by an increase in Na+ entry into the cells. The effect of bombesin on Na+ entry and Na+/K+ pump activity was concentration dependent with half-maximal stimulation occurring at 0.3-0.4 nM. The structurally related peptides litorin, gastrin-releasing peptide, and neuromedin B also stimulated ouabain-sensitive 86Rb+ uptake; the relative potencies of these peptides in stimulating the Na+/K+ pump were comparable to their potencies in increasing DNA synthesis. Bombesin increased Na+ influx, at least in part, through an Na+/H+ antiport. The peptide augmented intracellular pH and this effect was abolished in the absence of extracellular Na+. In addition to monovalent ion transport, bombesin and the structurally related peptides rapidly increased the efflux of 45Ca2+ from quiescent Swiss 3T3 cells. This Ca2+ came from an intracellular pool and the efflux was associated with a 50% decrease in total intracellular Ca2+. The peptides also caused a rapid increase in cytosolic free calcium concentration. Prolonged pretreatment of Swiss 3T3 cells with phorbol dibutyrate, which causes a loss of protein kinase C activity, greatly decreased the stimulation of 86Rb+ uptake and Na+ entry by bombesin implicating this phosphotransferase system in the mediation of part of these responses to bombesin. Since some activation of monovalent ion transport by bombesin was seen in phorbol dibutyrate-pretreated cells, it is likely that the peptide also stimulates monovalent ion transport by a second mechanism

  13. Ouabain enhancement of compound 48/80 induced histamine secretion from rat peritoneal mast cells

    Purified populations of rat peritoneal mast cells were used to study the effect of ouabain on compound 48/80-induced histamine secretion and on 86Rb+ uptake. 86Rb+ was used as a tracer for extracellular K+. The calculated value of the ouabain-sensitive uptake of K+ and 86Rb+ was considered a measure of the Na+-K+ pump activity of the cells. Ouabain caused an immediate inhibition of the pump activity and a time-dependent increase in histamine secretion in the absence of extracellular calcium. No effect on the secretion was observed in the presence of calcium. The effect of ouabain on the secretion occurs in the presence of sodium but not when sodium was replaced by lithium. Preservation by ouabain of a high intracellular sodium content in sodium-loaded cells was associated with preservation of the secretory response in a calcium-free medium. In the presence of lanthanum in a calcium-free medium, the pump activity was inhibited and the enhancement by ouabain of the secretion of histamine was blocked. A less marked inhibition of the pump was found in a calcium-free medium containing magnesium. The inhibition exerted by magnesium was concentration-dependent (0-5 mM) as was the counteraction of magnesium of the enhancement of ouabain of the secretion of histamine. These observations indicate that the echancement by ouabain of the secretory response of mast cells preincubated in a calcium-free medium is associated with accumulation of sodium inside the cell. In addition to a decreased rate of sodium-calcium exchange caused by a decreased inward directed sodium gradient, the mechanism by which ouabain enhances the secretory response is likely to involve an increased binding of calcium to membrane binding sites. (au)

  14. Perfusion changes in the RIF-1 tumour and normal tissues after carbogen and nicotinamide, individually and combined.

    Honess, D. J.; Bleehen, N.M.

    1995-01-01

    The strategy of combining carbogen breathing and nicotinamide to overcome chronic and acute hypoxia respectively is being evaluated clinically. The effects of both agents individually and in combination on relative perfusion of 400-700 mm3 RIF-1 tumours and normal tissues were measured by 86Rb extraction. Carbogen breathing alone for 6 min increased relative tumour perfusion by 50-70% compared with control at flow rates of 50 to 200 ml min-1, but the effect was lost at 300 ml min-1. All flow ...

  15. Blood flow modification by nicotinamide and metoclopramide in mouse tumours growing in different sites.

    Hirst, D G; Joiner, B.; Hirst, V. K.

    1993-01-01

    Nicotinamide (NA) and metoclopramide (MCA) have been shown to be sensitisers of the effects of radiation and drugs in experimental rodent tumours growing in skin and muscle. We have used 86Rb uptake to investigate the effects of these two drugs on the distribution of blood to a mouse carcinoma (NT) growing in skin, muscle or the gut wall, as well as to the host normal tissue. NA caused an increase in cardiac output distribution (COD) of between 17 and 92% to tumours in the three sites. When t...

  16. Radionuclides for investigating the accumulation of toxic elements in algae and fish

    Radionuclides are very suitable for investigating the accumulation of toxic elements in algae and fish. The most important results obtained from using 51Cr(III) (VI), 65Zn, 74As(III) (V), CH374AsO(OH)2, (CH3)274AsO(OH), (CH3)374As, 85Sr, 86Rb, /sup 115m/Cd, 133Ba, 137Cs, 203Hg(II), CH3203HgCl and C6H5203HgCl for the study of the accumulation, release and chemical transformation of the above species in algae and fish are summarized. (author)

  17. Radionuclides in the investigation of the cumulation of toxic elements on alga and fish

    The present paper surveys the most important results obtained using 51Cr(III)(VI), 65Zn, 74As(III)(V), CH374AsO(OH)2, (CH3)274AsO(OH), (CH3)374As, 85Sr, 86Rb, /sup 115m/Cd, 133Ba, 137Cs, 203Hg(II), CH3203HgCl and C6H5203HgCl for studying the cumulation, release and chemical transformation of the above species on alga and fish. (author)

  18. Influence of complex formation on extraction of some fission products by sorption on inorganic sorbents

    Sorption of fission products of radionuclides 137Cs, 89,90Sr, 90,91Y, 86Rb, 133Ba, 95Zr+95Nb, 95Nb, 103,106Ru, 141,144Ce, 115mCd, 113Sn, 125Sb by hydroxides Fe(III), Mn(IV) on the background of 1 mol/l of NaNO3 at the pretense of ions SO42-, C2O42- at a wide ph range (1+14) is studied in present work. Optimal conditions of extraction of each radionuclide by sorption on inorganic sorbents are defined.

  19. The use of radiotracers in natural rubber research in Malaysia

    Five main areas where radiotracers have been used in research on natural rubber are on studies on the uptake of plant nutrients by Hevea brasiliensis using 32P, 86Rb and 45Ca as tracers; biosynthesis of Hevea rubber using 14C or 3H labelled intermediates; translocation and metabolism of 14C. Ethephon in Hevea brasiliensis; use of radiotracers as analytical tools and adsorption of labelled fatty acid soaps on natural rubber lattices. These studies are discussed to show the powerful tool that radiotracers provide in agricultural, biochemical and chemical research on natural rubber. (author)

  20. Radioassay of dual-labeled samples with a Cherenkov counting technique

    A new Cherenkov counting technique which allows radioactivities of a dual-labeled sample to be determined simultaneously by using a wavelength shifter has been proposed, and tested for the pairs 32P-36Cl and 86Rb-36Cl. The minimum requirements for this method are a single channel liquid scintillation counter, a wavelength shifter and a reference sample for determining the Cherenkov counting efficiency. The simple procedure for sample preparation and measurement makes the technique very useful for routine radioassay with the help of a desk-top computer. (orig.)

  1. Triton X-100 as a complete liquid scintillation cocktail for counting aqueous solutions and ionic nutrient salts

    Triton X-100, used alone, was found to act as a complete liquid scintillation cocktail. Triton X-100 acted as a scintillator and the effect was not due to Cerenkov radiation. A variety of other commercially available surfactants also acted as scintillators, but with different levels of efficiency. Triton X-100/water combinations were suitable for counting aqueous solutions of 33P and 86Rb and the count rate was stable over extended periods of time. Triton X-100/toluene combinations also yielded high counting efficiencies. Triton X-100 was more sensitive to quenching than standard cocktails containing fluors. (author)

  2. Intestinal excretion of metals by rats

    The excretion of 65Zn, sup(115m)Cd, 203Hg, 207Bi, 210Pb, 60Co, 64Cu, 85Sr and 86Rb in the perfused sections of the intestinal tract in vivo was investigated by the pendular perfusion method. After intravenous administration the excretion of metals was investigated in the jejunum, in the colon and in some experiments also in the ileum. The fluid net movement in the jejunum and colon was measured in dependency on the energy spectrum of the applied metal isotope by means of 14C or 3H-polyethylene glycol 2000. (orig./MG)

  3. A quantitative radiochemical study of ionic and molecular transport in bovine dental enamel

    A radiochemical method was developed to determine quantitatively and simultaneously the transport of up to four different compounds through dental enamel. The compounds chosen were [3H]-sorbitol, [14C]-glycerol, 36Cl- and 86Rb+. Effective diffusion coefficients of these compounds determined at 40C were considerably different for different specimens of enamel. Thus values for [3H]-sorbitol varied for 0.04 x 10-8 to 2.5 x 10-8 cm2s-1. Most enamel membranes showed an ion selective behaviour by which the cations were more mobile than the anions. A molecular sieve effect was observed for glycerol and sorbitol. (author)

  4. Ouabain-binding and 86rubidium-uptake in lymphocytes of normal and borderline hypertensive subjects

    Nielsen, J R; Pedersen, K E; Johansen, Torben;

    1983-01-01

    In borderline hypertensives cellular sodium concentration seems to be increased, indicating that cellular abnormalities are present in the early course of essential hypertension. In order to study the mechanisms underlying this finding the number of sodium/potassium pump sites and the cation pump...... activity were studied in lymphocytes of nine borderline hypertensives (27 (20-36) years) and nine controls (28 (20-36) years). Maximum 3H-ouabain binding and 86Rb-uptake were taken as measures of the number of pump sites and cation pump activity, respectively. The median number of sodium/potassium pump...

  5. Na+ pump in renal tubular cells is regulated by endogenous Na+-K+-ATPase inhibitor from hypothalamus

    Bovine hypothalamus contains a high affinity, specific, reversible inhibitor of mammalian Na+-K+-ATPase. Kinetic analysis using isolated membrane fractions showed binding and dissociation rates of the hypothalamic factor (HF) to be (like ouabain) relatively long (off rate = 60 min). To determine whether the kinetics of inhibition in intact cells might be more consistent with regulation of physiological processes in vivo, binding and dissociation reactions of HF in intact renal epithelial cells (LLC-PK1) were studied using 86Rb+ uptake and [3H]ouabain binding. As with membranes, a 60-min incubation with HF inhibited Na+-K+-ATPase in LLC-PK1 cells. In contrast to membrane studies, no prolonged incubation with LLC-PK1 was needed to observe inhibition of Na+-K+-ATPase. HF caused a 33% inhibition of ouabain-sensitive 86Rb+ influx within 10 min. Incubation of cells with HF followed by washout showed rapid reversal of pump inhibition and a doubling of pump activity. The dose-response curve for HF inhibition of LLC-PK186Rb+ uptake showed a sigmoidal shape consistent with an allosteric binding reaction. Thus HF is a potent regulator of Na+-K+-ATPase activity in intact renal cells, with binding and dissociation reactions consistent with relevant physiological processes

  6. Evidence for coordinate genetic control of Na,K pump density in erythrocytes and lymphocytes

    The erythrocyte is widely used as a model cell for studies of the Na,K pump in health and disease. However, little is known about the factors that control the number of Na,K pumps expressed on the erythrocytes of a given individual, nor about the extent to which erythrocytes can be used to validly assess the pump density on other cell types. In this report, the authors have compared the interindividual variance of Na,K pump density in erythrocytes of unrelated individuals to that seen with identical twins. Unlike unrelated individuals, in whom pump parameters, i.e., ouabain binding sites, 86Rb uptake, and cell Na concentration vary widely, identical twin pairs showed no significant intrapair variation for these values. Thus, a role for genetic factors is suggested. In addition, the authors established and validated a method for determining Na,K pump density and pump-mediated 86Rb uptake in human peripheral lymphocytes. Using this method, they show that whereas Na,K pump density differs markedly between erythrocytes (mean of 285 sites per cell) and lymphocytes (mean 40,600 sites per cell), there is a strong and highly significant correlation (r = 0.79, P less than 0.001) between the pump density in these cell types in any given individual. Taken together, these studies suggest that genetic factors are important determinants of Na,K pump expression, and that pump density appears to be coordinately regulated in two cell types in healthy individuals

  7. Evidence for coordinate genetic control of Na,K pump density in erythrocytes and lymphocytes

    DeLuise, M.; Flier, J.S.

    1985-08-01

    The erythrocyte is widely used as a model cell for studies of the Na,K pump in health and disease. However, little is known about the factors that control the number of Na,K pumps expressed on the erythrocytes of a given individual, nor about the extent to which erythrocytes can be used to validly assess the pump density on other cell types. In this report, the authors have compared the interindividual variance of Na,K pump density in erythrocytes of unrelated individuals to that seen with identical twins. Unlike unrelated individuals, in whom pump parameters, i.e., ouabain binding sites, /sup 86/Rb uptake, and cell Na concentration vary widely, identical twin pairs showed no significant intrapair variation for these values. Thus, a role for genetic factors is suggested. In addition, the authors established and validated a method for determining Na,K pump density and pump-mediated /sup 86/Rb uptake in human peripheral lymphocytes. Using this method, they show that whereas Na,K pump density differs markedly between erythrocytes (mean of 285 sites per cell) and lymphocytes (mean 40,600 sites per cell), there is a strong and highly significant correlation (r = 0.79, P less than 0.001) between the pump density in these cell types in any given individual. Taken together, these studies suggest that genetic factors are important determinants of Na,K pump expression, and that pump density appears to be coordinately regulated in two cell types in healthy individuals.

  8. Potassium fluxes in Chlamydomonas reinhardtii. II. Compartmental analysis

    42K+ and 86Rb+ were used to determine the subcellular distribution of potassium in Chlamydomonas reinhardtii by compartmental analysis. In both wild type and a mutant strain, three distinct compartments (referred to as I, II, and III) were apparent. Using 42K+, we found that these had half-lives for K+ exchange of 1.07 min, 12.8 min, and 2.9 h, respectively, in wild-type cells and 0.93 min, 14.7 min, and 9.8 h, respectively, for the mutants. Half-lives were not significantly different when 86Rb+ was used to trace K+. Compartments I and II probably correspond to the cell wall and cytoplasm, respectively. Based on the lack of a large central vacuole in Chlamydomonas, the effect of a dark pretreatment on the kinetic properties of compartment III and the similarity between the [K+] of compartment III and that of isolated chloroplasts, this slowly exchanging compartment was identified as the chloroplast. Growth of wild-type cells at 100 micromolars (instead of 10 mM K+) caused no change of cytoplasmic [K+] but reduced chloroplast [K+] very substantially. The mutants failed to grow at 100 micromolars K+

  9. Inhibition of cation channel function at the nicotinic acethylcholine receptor from Torpedo: Agonist self-inhibition and anesthetic drugs

    Modulation of the nicotinic acethylcholine receptor from Torpedo by cholinergic agonists, local anesthetics, and n-alkanols was studied using 86Rb+ flux studies in sealed native Torpedo electroplaque membrane vesicles. Reliable concentration-response and kinetic data were obtained using manual ten sec filtration assays in vesicles partially blocked with alpha-bungarotoxin to remove spare receptors and quenched-flow assays to assess initial 86Rb+ flux rates or the rate of drug-induced receptor inactivation. Concentration response relationships for the agonists acetylcholine, carbamylcholine, suberyldicholine, phenyltrimethylammonium, and (-)-nicotine are all bell-shape due to stimulation of cation channel opening at low concentrations and inhibition of channels at higher concentrations. The rate of agonist-induced fast desensitization (kd) increases with [acetylcholine] in parallel with channel activation, suggesting that desensitization proceeds from the open state and/or states in rapid equilibrium with it. At self-inhibitory acetylcholine concentrations, a new rapid inactivation (rate = kf) is observed before fast desensitization. The rate and extent of rapid inactivation is compatible with bimolecular association between acethylcholine and inhibitory site with KB = 40 mM

  10. Stimulation of cation transport in mitochondria by gramicidin and truncated derivatives

    Gramicidin and the truncated derivatives desformylgramicidin (desfor) and des(formylvalyl)gramicidin (desval) stimulate monovalent cation transport in rat liver mitochondria. Cation fluxes were compared indirectly from the effect of cations on the membrane potential at steady state (state 4) or from the associated stimulation of electron transport. Rb+ transport was measured directly from the uptake of 86Rb. The truncated gramicidins show enhanced selectivity for K+ and Rb+ when compared to gramicidin. Moreover, the pattern of selectivity within the alkali cation series is altered. The cation fluxes through the truncated derivatives are more strongly dependent on the cation concentration. The presence of high concentrations of permeating cation enhances the transport of other cations through the truncated derivative channels, suggesting that cations are required for stabilizing the channel structure. In high concentrations of KCl, desfor and desval are nearly as effective as gramicidin in collapsing the mitochondrial membrane potential, and consequently, in the uncoupling of oxidative phosphorylation and enhancement of ATP hydrolysis. Preliminary experiments with liposomes show that 86Rb exchange is stimulated by desfor and desval almost to the same extend at gramicidin. These results strongly suggest that the truncated gramicidins form a novel conducting channel which differs from the gramicidin head-to-head, single-stranded β6.3-helical dimer (channel) in its conductance characteristic and its structure. On the basis of the secondary structure of the truncated derivatives, the authors suggest that the antiparallel double-stranded helix dimer (pore) is a likely alternative structure for this novel channel

  11. Excitation functions of some neutron threshold reactions on 89Y in the energy range of 7.8 to 14.7 MeV

    Excitation functions were measured for 89Y(n,2n)88Y, 89Y(n,p)89Sr and 89Y(n,α)86Rb reactions from their respective thresholds up to 14.7 MeV using the activation technique. Quasi-monoenergetic neutrons in the energy range of 7.8 to 13.3 MeV were produced via the 2H(d,n)3He reaction on a D2 gas target at the Juelich compact cyclotron (CV 28), and monoenergetic neutrons in the range of 13.8 to 14.7 MeV using the D-T neutron generator at Debrecen. For characterization of 88Y and 86Rb, high-resolution γ-ray spectrometry was applied. The latter product was also separated radiochemically and characterized by low-level β- counting; the results obtained using the two counting methods were generally in good agreement. The product 89Sr is a pure β- emitter: its activity was exclusively assayed via radiochemical separation and β- counting. Our results agree with the literature values on the (n,2n) reaction and provide the first consistent set of data on the (n,p) and (n,α) reactions near their thresholds. Statistical model calculations incorporating precompound effects were performed on the three excitation functions under consideration. The experimental and theoretical results were found to be in good agreement. Some systematic trends in the excitation functions in this mass region are discussed. (orig.)

  12. Rho family GTP binding proteins are involved in the regulatory volume decrease process in NIH3T3 mouse fibroblasts

    Pedersen, Stine F; Beisner, Kristine H; Willumsen, Berthe M;

    2002-01-01

    kinase inhibitor Y-27632 and the phosphatidyl-inositol 3 kinase (PI3K) inhibitor wortmannin. The maximal rates of swelling-activated K+ (86 Rb+ as tracer) and taurine ([3H]taurine as tracer) efflux after a 30 % reduction in extracellular osmolarity were increased about twofold in cells with maximal Rho......AV14 expression compared to wild-type cells, but were unaffected by Y-27632. The volume set points for activation of release of both osmolytes appeared to be reduced by RhoAV14 expression. The maximal taurine efflux rate constant was potentiated by the tyrosine phosphatase inhibitor Na(3)VO(4), and...... inhibited by the tyrosine kinase inhibitor genistein. The magnitude of the swelling-activated Cl- current (I(Cl,swell) ) was higher in RhoAV14 than in wild-type cells after a 7.5 % reduction in extracellular osmolarity, but, in contrast to 86Rb+ and [3H]taurine efflux, similar in both strains after a 30...

  13. Studies on the methods of inorganic nutrient application in coconut

    Using carrier free 32P, tagged single superphosphate and 86Rb, the efficiency of different methods of plant injection and soil placement techniques for fertilizer applications was examined. In the plant injection techniques the radioactivity was fed to the palms through growing roots tips, cut ends of roots, stem injection and leaf axils. The application of radioactivity through the cut ends of roots was most efficient since 32P was detected in 10 m tall palms, four hours after application. In stem, leaf axil and growing roots tips injection the 32P was detected after 8, 12 and 18 h. Out of four methods of soil application, the quickest recovery of 32P in the palms was detected after 7 days of placement when applied by the hole method. The 32P activity in the palms through circular trenches, strips and basin methods was recorded after 8, 8 and 11 days of application respectively. The accumulation of 86Rb was significantly higher than 32P. With plant injection technique the accumulation of activity was found to be significantly higher than with soil placement methods. The rate of radioactivity absorption was 10 to 60 time faster in the former technique as compared to that of the latter. The application of radioactivity through cut ends of roots and circular trench methods, were found to be better and may recommended for nutrient application in coconut. (orig.)

  14. Actions of ionomycin in rat parotid gland

    Poggioli, J.; Leslie, B.A.; McKinney, J.S.; Weiss, S.J.; Putney, J.W. Jr.

    1982-04-01

    The effects of ionomycin (SQ 23,377), a carboxylic acid Ca-ionophore, on the rat parotid acinar cell were investigated. Ionomycin stimulated 86Rb efflux from parotid slices and was substantially more potent and efficacious than the Ca-ionophore, A-23187. The release of 86Rb was dependent on the concentration of ionomycin and of Ca. Ionomycin also stimulated 22Na uptake and 3H-protein secretion, but did not stimulate the incorporation of 32PO4 into phosphatidylinositol. These observations are consistent with an action of ionomycin in increasing cytosolic Ca by acting as an ionophore and not involving endogenous receptors. Pretreatment with ionomycin inhibited the transient, Ca-independent responses to carbachol or physalaemin. When ionomycin was added to parotid cells pre-equilibrated with 45Ca, a net loss of radiocalcium was observed. These observations suggest that ionomycin can release the receptor-regulated cellular Ca pool. Morphological studies did not reveal any nonspecific deleterious effects in the cells after incubation with 2.67 microM ionomycin.

  15. Lysophosphatidylcholines containing polyunsaturated fatty acids were found as Na+,K+-ATPase inhibitors in acutely volume-expanded hog

    Na+,K+-ATPase inhibitors activities against the specific binding of ouabain to Na+,K+-ATPase and 86Rb uptake into hog erythrocytes have been purified from the plasma of acutely saline-infused hog. The purifications were performed by a combination of Amberlite XAD-2 adsorption chromatography and four steps of high-performance liquid chromatography with four different types of columns. Fast atom bombardment (FAB) mass and proton NMR spectrometric studies identified the purified substances as γ-arachidoyl- [LPCA(γ), 34%], β-arachidoyl- [LPCA(β), 4%], γ-linoleoyl- (LPCL, 33%), and γ-oleoyl- (LPCO, 25%) lysophosphatidylcholine, expressed in molar ratio in the plasma. Small amounts of γ-docosapentaenoyl-, γ-eicosatrienoyl-, and γpalmitoyllysophosphatidylcholine were also detected by both FAB mass and 1H NMR spectrometric studies. The inhibition of Na+,K+-ATPase activity due to these compounds was always more sensitive than that of both ouabain-binding and 86Rb uptake activities. The ouabain-displacing activity in plasma due to these compounds increased with time during saline infusion. The maximal plasma level was approximately 10 times higher than that in the preinfusion plasma sample. Although these results suggest that γ-acyl-LPC's with long-chain polyunsaturated fatty acids are not simple competitive inhibitors to Na+,K+-ATPase, these compounds could be implicated in the pathogenesis of the circulation abnormality through the modulation of membrane enzyme

  16. Inhibition of Na(+) -K+ pump activity by divalent cations in intact peritoneal mast cells of the rat

    Knudsen, T; Berthelsen, Carsten; Johansen, Torben

    1990-01-01

    1. The inhibition by the divalent cations magnesium, barium and strontium and the trivalent ion lanthanum of the Na(+) -K+ pump in the plasma membrane of rat peritoneal mast cells was studied in pure mast cell populations by measurement of the ouabain-sensitive uptake of the radioactive potassium......-resistant uptake was not changed. Half maximum decrease in the ouabain-sensitive K+(86Rb+)-uptake was observed with 1.8 mM magnesium, 1.2mM barium and 0.7 mM strontium. 4. The trivalent ion lanthanum blocked almost completely the ouabain-sensitive K+(86Rb+)-uptake at a concentration of 1 microM as does 1 m......M calcium. Combining either of these ions with magnesium had no further inhibitory effect on the ouabain-sensitive uptake. 5. In conclusion, in addition to the previously suggested modulation by calcium of the activity of the Na+ (-)K+ pump, evidence is provided in this investigation that the modulation may...

  17. The effects of digoxin and β-methyldigoxin on the heart rate of decompensated patients with atrial fibrillation

    Eighteen patients with atrial fibrillation were given digoxin 0.13 mg twice daily for 3 weeks and β-methyldigoxin 0.10 mg twice daily for another 3 weeks. At the end of each 3 week period an exercise test was performed and the effects on the heart rate of the two drugs were compared. No difference in heart rate was obtained at rest, wheareas the heart rate after 6 min of exercise was higher during treatment with digoxin (131 beats/min) than when the patients were taking β-methyldigoxin (124 beats/min). There were no significant differences between digoxin and β-methyldigoxin in their effects on the ECT (R-R intervals, T-wave, Q-T duration). The plasma concentrations of the two glycosides were determined by radioimmunoassay and by 86Rb-uptake inhibition assay. Comparable plasma concentration values (1.0 ng/ml for digoxin, 1.1 ng/ml for β-methyldigoxin, mean values) were obtained by radioimmunoassay, but the 86Rb-technique gave significantly higher values (mean 1.5 ng/ml) for β-methyldigoxin. It is concluded that β-methyldigoxin is equal to digoxin for producing slowing of the heart rate in patients with atrial fibrillation. (orig.)

  18. Changes in cardiovascular function and vascular Na-K pump activity in streptozotocin (STZ)-diabetic rats

    Blood pressure, vascular reactivity and Na-K pump function were examined in male Sprague-Dawley rats and rats made diabetic with a single dose of STZ (50 mg/Kg, I.V.). In each group, body weight, systolic blood pressure and heart rate were determined weekly, and serum glucose was measured biweekly for 12 weeks. Contractile responses and Na-K pump activity of vascular smooth muscle were studied in caudal artery strips. At 12 weeks after treatment, STZ rats had elevated serum glucose but decreased body weight and heart rate in comparison to control rats. Systolic blood pressure of STZ rats was not significantly increased at any time during the treatment period. Contractile responses of caudal artery strips to norepinephrine and serotonin did not indicate altered sensitivity (ED50) of vascular smooth muscle in STZ rats. The responsiveness (g tension/g wet wt.), however, was significantly increased in artery strips from STZ rats. Analysis of ouabain-inhibitable 86Rb-uptake of caudal artery by the double-reciprocal plot showed that neither the rate of 86Rb-uptake nor the affinity for rubidium were altered by STZ treatment. The data indicate that nonspecific increases in the reactivity of caudal arteries to excitatory agents occur in diabetic rats which may precede the development of hypertension. The enhanced reactivity is not associated with alteration of the vascular Na-K pump activity

  19. Potassium transport across rat alveolar epithelium: evidence for an apical Na+-K+ pump.

    Basset, G; Bouchonnet, F; Crone, C; Saumon, G

    1988-06-01

    1. Experiments were performed on rat lungs into which various solutions were instilled whilst the lungs were perfused with either whole blood or Ringer solution. Instillation of ion-free glucose solution led to a net flux of fluid and ions into the alveolar spaces. K+ ions entered faster than Na+ ions and reached a concentration about twice that in the perfusate. Ouabain in the perfusate (basolateral side) prevented the rise in alveolar K+ concentration above that in the perfusate, indicating a transcellular pathway. Ba2+ in the instillate (apical side) hindered the entry of K+ into alveoli, suggesting the presence of apical K+ channels. 2. When Ringer solution was instilled, K+ was continuously removed from the alveoli and the K+ concentration in the instillate remained constant or decreased slightly depending on the rate of fluid absorption. The net K+ efflux from alveoli to blood was 0.23 pmol/(cm2 s). When Ba2+ was added to the instillate the net K+ efflux increased to 0.36 pmol/(cm2 s). Apical ouabain reversed the K+ flux resulting in a net K+ flux of 0.19 pmol/(cm2 s) into the alveoli. This suggests the presence of an Na+-K+-ATPase located in the apical membrane of some alveolar cells. 3. The K+ transport from instillate (Ringer solution) to perfusate was traced by means of 86Rb which was added to the instillate. Ouabain in the instillate did not affect fluid absorption but reduced the apparent 86Rb permeability by 50% although the paracellular permeability (estimated with [3H]mannitol) was unaffected. This also indicates the presence of an apical Na+-K+-ATPase. When ouabain was added to the perfusate, the apparent 86Rb permeability doubled. These findings indicate that recirculation of 86Rb (and K+) occurs due to the activity of both apical and basolateral Na+-K+-ATPases. 4. When ouabain was placed on both sides of the epithelium, preventing transcellular transport, the passive 86Rb permeability was 10.3 x 10(-8) cm/s (assuming an alveolar surface area of

  20. Chromatographic purification of neutron capture molybdenum-99 from cross-contaminant radionuclides

    Technetium-99m is called the work horse, for many reasons, in nuclear medicine diagnostic purposes. It is produced as the β-decay of 99Mo radionuclide. Molybdenum-99 gel type generators are considered as a suitable alternative of the conventional chromatographic alumina columns loaded with fission molybdenum-99. 99Mo neutron-capture is cross-contaminated with radionuclides originated from activation of chemical impurities in the Mo target such 60C0, 65Zn, 95Zr, 175Hf, 181Hf, 86Rb, 134Cs, 141Ce, 152Eu, 140La,51Cr, 124Sb,46Sc, 54Mn, 59Fe and / or fast neutrons interactions with the stable isotopes of molybdenum such as 92mNb, 95Nb and 95Zr. To prevent contamination of the eluted 99mTc, successive purification methods were made. After complete dissolution of the irradiated target wrapped with thin Al foil in 5 M NaOH solution, hydrogen peroxide was added to start precipitation of Fe(OH)3. The formed Fe (III) minerals allow complete elimination of some radio contaminants from the molybdate solute such as 152Eu, 140La,141Ce, 45Mn and 92mNb in addition to partial elimination of 46Sc, 60Co and 59Fe radionuclides. The remaining supernatant was acidified by concentrated nitric acid to ph 9.5 for precipitation of Al(OH)3 with complete elimination of radio contaminants such as 95Zr 175Hf, 181Hf, 65Zn, 124Sb, 51Cr, 46Sc, 60Co and 59Fe. 134Cs and 86Rb radionuclides were not affected by precipitation of Fe(OH)3 or Al(OH)3. Chromatographic column of potassium nickel hexacyanoferrate (II) (KNHCF) has high affinity towards elimination of 134Cs and 86Rb radionuclides. Highly pure molybdate-99Mo solution was processed for preparation of zirconium molybdate gel generator with 99mTc eluate of high radionuclidic, radiochemical and chemical purity suitable for use in medical purposes.

  1. Early events elicited by bombesin and structurally related peptides in quiescent Swiss 3T3 cells. II. Changes in Na/sup +/ and Ca/sup 2 +/ fluxes, Na/sup +//K/sup +/ pump activity, and intracellular pH

    Mendoza, S.A.; Schneider, J.A.; Lopez-Rivas, A.; Sinnett-Smith, J.W.; Rozengurt, E.

    1986-06-01

    The amphibian tetradecapeptide, bombesin, and structurally related peptides caused a marked increase in ouabain-sensitive /sup 86/Rb/sup +/ uptake (a measure of Na/sup +//K/sup +/ pump activity) in quiescent Swiss 3T3 cells. This effect occurred within seconds after the addition of the peptide and appeared to be mediated by an increase in Na/sup +/ entry into the cells. The effect of bombesin on Na/sup +/ entry and Na/sup +//K/sup +/ pump activity was concentration dependent with half-maximal stimulation occurring at 0.3-0.4 nM. The structurally related peptides litorin, gastrin-releasing peptide, and neuromedin B also stimulated ouabain-sensitive /sup 86/Rb/sup +/ uptake; the relative potencies of these peptides in stimulating the Na/sup +//K/sup +/ pump were comparable to their potencies in increasing DNA synthesis. Bombesin increased Na/sup +/ influx, at least in part, through an Na/sup +//H/sup +/ antiport. The peptide augmented intracellular pH and this effect was abolished in the absence of extracellular Na/sup +/. In addition to monovalent ion transport, bombesin and the structurally related peptides rapidly increased the efflux of /sup 45/Ca/sup 2 +/ from quiescent Swiss 3T3 cells. This Ca/sup 2 +/ came from an intracellular pool and the efflux was associated with a 50% decrease in total intracellular Ca/sup 2 +/. The peptides also caused a rapid increase in cytosolic free calcium concentration. Prolonged pretreatment of Swiss 3T3 cells with phorbol dibutyrate, which causes a loss of protein kinase C activity, greatly decreased the stimulation of /sup 86/Rb/sup +/ uptake and Na/sup +/ entry by bombesin implicating this phosphotransferase system in the mediation of part of these responses to bombesin. Since some activation of monovalent ion transport by bombesin was seen in phorbol dibutyrate-pretreated cells, it is likely that the peptide also stimulates monovalent ion transport by a second mechanism.

  2. Effect of temperature and light on foliar absorption of P and Rb by Chrysanthemum and Pilea

    Szczepan Marczyński

    2013-12-01

    Full Text Available Young plants of Pilea cadierei Gagnep Guillaum and Chrysanthemum morifolium Ramat. 'Giant # 4 Indianapolis White' were grown in Hoagland's solution in growth chambers. Their leaves were treated with rubidium phosphate double labelled with 33P and 86Rb. Light intensity, period of pretreatment in light or dark, daylength, and air temperature had different influences on foliar uptake of each ion, as did plant species and leaf surface. With all variables tested, uptake and translocation of Rb was much greater than of P. Absorption of both P and Rb through the lower surface was as much as 8 times greater than through upper surface, especially with Pilea. Light had a greater effect upon uptake of both P and Rb by Chrysanthemum than by Pilea, but did not influence uptake as much as previously reported.

  3. The effect of ultraviolet radiation on early stages of activation of human lymphocytes: inhibition is independent of effects on DNA

    Castellanos, G; Owens, T; Rudd, C;

    1982-01-01

    before mitogen was added to the cultures, but were unaffected if irradiation occurred after 16 h of culture in presence of Con A. Cells irradiated with 84 ergs/mm2 at the onset of culture with mitogen did not show the early increase of cation pump function which is a characteristic of stimulated......Low doses (30-84 ergs/mm2, 1 erg = 10(7) J) of ultraviolet radiation (UV) caused severe inhibition of the proliferation of human lymphocytes in vitro. Greatest inhibition was produced when resting cells were irradiated immediately prior to stimulation with concanavalin A (Con A); this was true...... lymphocytes, when this was measured by means of 86Rb uptake after 2-4 h culture. The mitogen-stimulated activation of cation pump function has previously been shown to be unaffected by concentrations of cycloheximide and actinomycin D which produce virtually complete inhibition of protein and RNA synthesis...

  4. Diphenyleneiodonium, an inhibitor of NOXes and DUOXes, is also an iodide-specific transporter

    C. Massart

    2014-01-01

    Full Text Available NADPH oxidases (NOXes and dual oxidases (DUOXes generate O2.− and H2O2. Diphenyleneiodonium (DPI inhibits the activity of these enzymes and is often used as a specific inhibitor. It is shown here that DPI, at concentrations similar to those which inhibit the generation of O2 derivatives, activated the efflux of radioiodide but not of its analog 99mTcO4− nor of the K+ cation mimic 86Rb+ in thyroid cells, in the PCCl3 rat thyroid cell line and in COS cell lines expressing the iodide transporter NIS. Effects obtained with DPI, especially in thyroid cells, should therefore be interpreted with caution.

  5. Counting efficiency for radionuclides decaying by beta and gamma-ray emission

    In this paper, counting efficiency vs figure of merit for beta and gamma-ray emitters has been computed. It is assumed that the decay scheme has only a gamma level and the beta-ray emission may be coincident with the gamma-rays or the internal-conversion electrons. The radionuclides tabulated are: 20O, 20F, 28Al, 35P,41Ar, 42K, 47Se, 62Fe, 66Cu, 81Ge, 86Rb, 104Rh, 108Ru, 112Pd, 121Sn(m), 122In, 129I, 141Ce, 142Pr, 151Sm, 170Tm, 171Tm, 194Os, 203Hg, 205Hg, 210Pb, 225Ra, 244Am(m). It has been assumed that the liquid is a toluene based scintillator solution in standard glass vials containing 10 cm3. (Author)

  6. Water permeability of Na+-K+-2C1- cotransporters in mammalian epithelial cells

    Hammann, Steffen; Herrera-Perez, J.J.; Bundgaard, Magnus;

    2005-01-01

    Water transport properties of the Na+-K+-2Cl- cotransporter (NKCC) were studied in cultures of pigmented epithelial cells (PE) from the ciliary body of the eye. Here, the membrane that faces upwards contains NKCCs and can be subjected to rapid changes in bathing solution composition and osmolarity....... The anatomy of the cultured cell layer was investigated by light and electron microscopy. The transport rate of the cotransporter was determined from the bumetanide-sensitive component of 86Rb+ uptake, and volume changes were derived from quenching of the fluorescent dye calcein. The water...... permeability (Lp) of the membrane was halved by the specific inhibitor bumetanide. The bumetanide-sensitive component of the water transport exhibited apparent saturation at osmotic gradients higher than 200 mosmol l-1. Cell shrinkages produced by NaCl or KCl were smaller than those elicited by equi...

  7. Shrinkage insensitivity of NKCC1 in myosin II-depleted cytoplasts from Ehrlich ascites tumor cells

    Hoffmann, Else K; Pedersen, Stine F

    2007-01-01

    Protein phosphorylation/dephosphorylation and cytoskeletal reorganization regulate the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) during osmotic shrinkage; however, the mechanisms involved are unclear. We show that in cytoplasts, plasma membrane vesicles detached from Ehrlich ascites tumor cells (EATC......) by cytochalasin treatment, NKCC1 activity evaluated as bumetanide-sensitive (86)Rb influx was increased compared with the basal level in intact cells yet could not be further increased by osmotic shrinkage. Accordingly, cytoplasts exhibited no regulatory volume increase after shrinkage. In cytoplasts......, cortical F-actin organization was disrupted, and myosin II, which in shrunken EATC translocates to the cortical region, was absent. Moreover, NKCC1 activity was essentially insensitive to the myosin light chain kinase (MLCK) inhibitor ML-7, a potent blocker of shrinkage-induced NKCC1 activity in intact...

  8. Rubidium efflux from the alga Hydrodictyon reticulatum

    Compartmental analysis of 86Rb outflux into a non-radioactive medium suggests that the distribution of potassium (for which rubidium seems to be a satisfactory marker) in the alga Hydrodictyon reticulatum is uniform, i.e. at the medium conditions used (0.1 mM CaCl2, 0.1 mM NaCl and 1.0 mM KCl) the potassium concentration is practically equal in the cytoplasm and in the vacuole. The unidirectional potassium flux across the tonoplast (about one order of magnitude lower than that across the plasmalemma) thus appears to be passive and does not result in an appreciable electrochemical potential difference of the potassium ion. (author)

  9. Studies on the mechanisms of activation of potassium efflux and receptor-cytoskeleton association by aggregated immunoglobulin E-receptor complexes on rat basophilic leukemia cells

    Evidence for the activation of an outwardly-directed K+ permeability pathway was obtained by studying changes in plasma membrane potential that result from the aggregation of immunoglobulin E-complexes on rat basophilic leukemia cells. With the potential-sensitive dye, bisoxonol, we observe that activation by multivalent antigen causes membrane depolarization that is followed by a return towards the resting potential that we term repolarization. The depolarization response may reflect a Ca2+ influx pathway, and it exhibits the same antigen-dose dependence and temperature dependence as the degranulation response. The polarization phase of the membrane potential response is selectively inhibited by the K+ channel blockers quinidine and Ba2+ in parallel with their inhibition of the degranulation response, suggesting an important role for a K+ efflux pathway in antigen-stimulated degranulation. 86Rb+ efflux measurements were used to characterize the K+ permeability pathways responsible for the repolarization response

  10. Evaluation of blood-brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

    Dynamic positron tomography of the brain with /sup 82/Rb, obtained from a portable generator [/sup 82/Sr (25 days) - /sup 82/Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally be intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using /sup 82/Rb and positron emission tomography and corroborated by the accumulation of /sup 86/Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

  11. Evaluation of blood--brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

    Dynamic positron tomography of the brain with 82Rb, obtained from a portable generator [82Sr (25 days) -- 82Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally by intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using 82Rb and positron emission tomography and corroborated by the accumulation of 86Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

  12. Decontamination by shotblasting of radioactivity deposited on an asphalt road

    Long-lived fission products may be deposited in the environment after a serious reactor accident. From previous experiments it is known that if firehosing is to be used for decontamination it has to be done soon after the deposition. It is therefore worthwhile to study another decontamination method. An experimental study has been conducted of how well shotblasting can remove contamination from an asphalt road. In shotblasting a thin layer of the surface is loosened by the impact of small steel balls, and in the same procedure the surface dust is vacuumed up and the steel balls recovered. The contaminant was 86Rb, which behaves as caesium. As reference, the weathering of identical contamination on an asphalt road, a concrete road and a road covered with small concrete stones was studied concurrently. (author)

  13. Application of radioisotopes in entomology

    Radioisotope techniques are effective in entomology and studies on insects physiology. The study presents the use of radioisotopes in pest control programs: Methods of insects irradiation and the concept of biological half-life of the radioisotopes in comparison with physical half-life are explained. Main radioisotopes used in entomology are:3H, 14Ca, 32P, 35S, 38Cl. Other radioisotopes contributing to studies on insects are: 198Au, 134Cs, 131I, 86Rb, 65Zn, 59Fe, 45Ca, 24Na, 22Na. Radiation doses specific to each radioisotopes are given in tables. As an example of the application of radioisotopes in pest control: the determination of insects population density by means of releasing irradiated male insects than chasing them; studying of reproduction activity of Agrotis ipsilon; studying of egg laying of Heliocoverpa armigera moth. 15 refs. 2 figs. 2 tabs

  14. Use of radioisotopes in study of herbicide effect mechanism

    The degradation of 35S-prometryne in 8 agricultural crops and 3 woody species is explained. S released from the -SCH3 group was incorporated into cystine, a sulphate anion, and in plants from the family Brassicaceae into sinalbin and glucobrassicin. The main cause of resistance of Convolvulus arvensis to atrazine (labelled on rings with 14C) was its ability to degrade atrazine into non-toxic metabolites (hydroxyatrazine, conjugate with glutathione). Bidisin, Isobarnon and Suffix decreased the uptake, transport, and metabolism of phosphorus (32P), calcium (45Ca) and potassium (86Rb) in Avena fatua; they are used for its killing. In barley and wheat no decrease was observed with the exception of a limited transport of potassium in the youngest leaf. Bidisin and Isobarnon inhibited the fixation of 14CO2 in A. fatua within 2 hours after application. (author)

  15. Increased digitalis-like activity in human cerebrospinal fluid after expansion of the extracellular fluid volume

    The present study was designed to determine whether acute expansion of the extracellular fluid volume influenced the digitalis-like activity of human cerebrospinal fluid (CSF), previously described. Human CSF samples, drawn before and 30 minutes after the intravenous infusion of 1 liter of either saline or glucose solutions, were assayed for digitalis-like activity by inhibition of either the 86Rb+ uptake into human erythrocytes or by the activity of a purified Na+-K+ ATPase. The CSF inhibitory activity on both systems significantly increased after the infusion of sodium solutions but did not change after the infusion of glucose. These results indicate that the digitalis-like factor of human CSF might be involved in the regulation of the extracellular fluid volume and electrolyte content and thereby in some of the physiological responses to sodium loading. 31 references, 2 figures, 1 table

  16. The effect of diamide on potassium transport and cellular morphology in mouse L-cells

    The effects of diamide (diazenedicarboxylic acid bis (N,N'-dimethylamide)) on the transport of potassium in mouse L-cells have been investigated using 86Rb+ as a tracer. Active, ouabain-sensitive uptake is reduced after 0.4 to 0.6 mol/L diamide treatment. The size of reduction depends on the temperature and the presence of glucose in the medium. These results suggest that the elimination of reduced glutathione by diamide is the major factor controlling the level of K+ transport in treated L-cells. In addition to decreasing active transport, diamide produces dramatic changes in cellular ultrastructure, probably through altered Na+/K+ balance and its action on tubulin. Clear organelle-free regions appear surrounded by vacuoles and swollen mitkchondria regions. The clear areas of cytoplasm eventually pinch off from the cell

  17. Application of neutron activation analysis for the determination of wines originating from different vineyards

    Neutron activation analysis has been used for the determination of trace elements in different wines originating from various french vineyards. Non-destructive technologies are used for short and middle half-life radionuclides (28Al - 76As - 49Ca - 38Cl - 42K - 27Mg - 56Mn - 24Na - 52V). A radiochemical separation is necessary for longer half-life radionuclides (60Co - 52Cr - 134Cs - 59Fe - 86Rb - 65Zn). The results of the study show that the identification of vineyards based on the determination of specific oligo-elements is feasible. However, more data are needed to demonstrate that the knowledge of the amounts of specific oligo-elements in a wine corresponding to a given vineyard can be used to disclose frauds, particularly in the cases of wine watering or mixtures of wines originating from different vineyards. (author)

  18. Biochemical analysis of SV40 small t mediated theophylline resistance in CV-1 cells

    The papovavirus SV40 encodes for the two tumor antigens, large T and small t. While much is known about large T, little information is available about the role of small t in the viral life cycle. The authors have developed a system for studying small t antigen based on its ability to overcome the G0 growth arrest induced by the methylxanthine, theophylline. Uninfected CV-1 cells, the permissive host for SV40, are arrested by 1-2mM theophylline. In contrast, Wt-infected cells are not arrested by the same concentrations of this drug. Biochemical studies were designed to analyze the effects of theophylline and the means by which small t can overcome the growth arrest of CV-1 cells. Theophylline, a cyclic AMP analogue, does not appear to arrest CV-1 cells by a cAMP-dependent mechanism. Theophylline appears to arrest CV-1 cells by inhibiting sodium influx. Both 86Rb+ and 22Na+ uptake were inhibited by theophylline. Amiloride and TMB-8, drugs which are known to inhibit the plasma membrane Na+/H+ antiporter, decreased 86Rb+ and 22Na+ uptake to the same degree as theophylline. Because these drugs also arrested mock and D1- but not Wt-infected cells it is possible that theophylline inhibits sodium uptake by inhibiting this antiporter. Furthermore, because Wt-infected cells are resistant to the growth arrest induced by these drugs, it is possible that small t acts either by directly altering this antiporter or by bypassing the step which requires the activity of the antiporter

  19. Chiral recognition of pinacidil and its 3-pyridyl isomer by canine cardiac and smooth muscle: Antagonism by sulfonylureas

    Steinberg, M.I.; Wiest, S.A.; Zimmerman, K.M.; Ertel, P.J.; Bemis, K.G.; Robertson, D.W. (Eli Lilly and Company, Indianapolis, IN (USA))

    1991-01-01

    Pinacidil, a potassium channel opener (PCO), relaxes vascular smooth muscle by increasing potassium ion membrane conductance, thereby causing membrane hyperpolarization. PCOs also act on cardiac muscle to decrease action potential duration (APD) selectively. To examine the enantiomeric selectivity of pinacidil, the stereoisomers of pinacidil (a 4-pyridylcyanoguanidine) and its 3-pyridyl isomer (LY222675) were synthesized and studied in canine Purkinje fibers and cephalic veins. The (-)-enantiomers of both pinacidil and LY222675 were more potent in relaxing phenylephrine-contracted cephalic veins and decreasing APD than were their corresponding (+)-enantiomers. The EC50 values for (-)-pinacidil and (-)-LY222675 in relaxing cephalic veins were 0.44 and 0.09 microM, respectively. In decreasing APD, the EC50 values were 3.2 microM for (-)-pinacidil and 0.43 microM for (-)-LY222675. The eudismic ratio was greater for the 3-pyridyl isomer than for pinacidil in both cardiac (71 vs. 22) and vascular (53 vs. 17) tissues. (-)-LY222675 and (-)-pinacidil (0.1-30 microM) also increased 86Rb efflux from cephalic veins to a greater extent than did their respective optical antipodes. The antidiabetic sulfonylurea, glyburide (1-30 microM), shifted the vascular concentration-response curve of (-)-pinacidil to the right by a similar extent at each inhibitor concentration. Glipizide also antagonized the response to (-)-pinacidil, but was about 1/10 as potent with a maximal shift occurring at 10 and 30 microM. Glyburide antagonized the vascular relaxant effects of 0.3 microM (-)-LY222675 (EC50, 2.3 microM) and reversed the decrease in APD caused by 3 microM (-)-LY222675 (EC50, 1.9 microM). Nitroprusside did not alter 86Rb efflux, and vascular relaxation induced by sodium nitroprusside was unaffected by sulfonylureas.

  20. Chiral recognition of pinacidil and its 3-pyridyl isomer by canine cardiac and smooth muscle: Antagonism by sulfonylureas

    Pinacidil, a potassium channel opener (PCO), relaxes vascular smooth muscle by increasing potassium ion membrane conductance, thereby causing membrane hyperpolarization. PCOs also act on cardiac muscle to decrease action potential duration (APD) selectively. To examine the enantiomeric selectivity of pinacidil, the stereoisomers of pinacidil (a 4-pyridylcyanoguanidine) and its 3-pyridyl isomer (LY222675) were synthesized and studied in canine Purkinje fibers and cephalic veins. The (-)-enantiomers of both pinacidil and LY222675 were more potent in relaxing phenylephrine-contracted cephalic veins and decreasing APD than were their corresponding (+)-enantiomers. The EC50 values for (-)-pinacidil and (-)-LY222675 in relaxing cephalic veins were 0.44 and 0.09 microM, respectively. In decreasing APD, the EC50 values were 3.2 microM for (-)-pinacidil and 0.43 microM for (-)-LY222675. The eudismic ratio was greater for the 3-pyridyl isomer than for pinacidil in both cardiac (71 vs. 22) and vascular (53 vs. 17) tissues. (-)-LY222675 and (-)-pinacidil (0.1-30 microM) also increased 86Rb efflux from cephalic veins to a greater extent than did their respective optical antipodes. The antidiabetic sulfonylurea, glyburide (1-30 microM), shifted the vascular concentration-response curve of (-)-pinacidil to the right by a similar extent at each inhibitor concentration. Glipizide also antagonized the response to (-)-pinacidil, but was about 1/10 as potent with a maximal shift occurring at 10 and 30 microM. Glyburide antagonized the vascular relaxant effects of 0.3 microM (-)-LY222675 (EC50, 2.3 microM) and reversed the decrease in APD caused by 3 microM (-)-LY222675 (EC50, 1.9 microM). Nitroprusside did not alter 86Rb efflux, and vascular relaxation induced by sodium nitroprusside was unaffected by sulfonylureas

  1. Study of Cleanup Procedures for Contaminated Areas: Examination of Rubidium as a Surrogate to Cesium

    A radiological weapon, or radiological dispersion device (RDD), is designed to spread radioactive materials (137Cs, 60Co, 241Am, 252Cf, 192Ir, 238Pu, 90Sr, 226Ra, etc) over a large area, in order to cause severe contamination. The dispersed radioactive material can be strongly bound to surfaces if not effectively removed shortly after the event. An effective decontamination agent for such cases is the commercial polymer Decongel-11011. It can be applied onto contaminated surfaces by brushing or spraying. Upon drying, it forms stable films that can be peeled off the surface, together with most of the contaminating materials. One of the most dangerous isotopes that can be used by terrorist to make a RDD is 137Cs 2. Therefore, it is important to examine the effectiveness of the polymer Decongel-1101 in removing it. Due to the difficulty in working with 137Cs in large scale experiments, It was suggested to replace it with the short lived radioisotope 86Rb (~18.6 days). This isotope is a good simulator for 137Cs, having similar chemical properties and migration behavior. This work is aimed at verifying whether 86Rb can indeed serve as a simulator to 137Cs in cleanup procedures of large contaminated areas. The first step will be a small scale comparison, on porous and non-porous surfaces, of the decontamination efficiency of this procedure tested on Rb versus Cs. These elements were spread on the examined surfaces as known concentration solutions of natural Rb and Cs salts. The decontamination efficiency was measured by peeling off the dry polymer and measuring the concentrations of the two elements in the polimer by various analytical methods

  2. C-peptide increases Na,K-ATPase expression via PKC- and MAP kinase-dependent activation of transcription factor ZEB in human renal tubular cells.

    Dana Galuska

    Full Text Available BACKGROUND: Replacement of proinsulin C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, conditions which are associated with a decrease in Na,K-ATPase activity. We determined the molecular mechanism by which long term exposure to C-peptide stimulates Na,K-ATPase expression and activity in primary human renal tubular cells (HRTC in control and hyperglycemic conditions. METHODOLOGY/PRINCIPAL FINDINGS: HRTC were cultured from the outer cortex obtained from patients undergoing elective nephrectomy. Ouabain-sensitive rubidium ((86Rb(+ uptake and Na,K-ATPase activity were determined. Abundance of Na,K-ATPase was determined by Western blotting in intact cells or isolated basolateral membranes (BLM. DNA binding activity was determined by electrical mobility shift assay (EMSA. Culturing of HRTCs for 5 days with 1 nM, but not 10 nM of human C-peptide leads to increase in Na,K-ATPase α(1-subunit protein expression, accompanied with increase in (86Rb(+ uptake, both in normal- and hyperglycemic conditions. Na,K-ATPase α(1-subunit expression and Na,K-ATPase activity were reduced in BLM isolated from cells cultured in presence of high glucose. Exposure to1 nM, but not 10 nM of C-peptide increased PKCε phosphorylation as well as phosphorylation and abundance of nuclear ERK1/2 regardless of glucose concentration. Exposure to 1 nM of C-peptide increased DNA binding activity of transcription factor ZEB (AREB6, concomitant with Na,K-ATPase α(1-subunit mRNA expression. Effects of 1 nM C-peptide on Na,K-ATPase α(1-subunit expression and/or ZEB DNA binding activity in HRTC were abolished by incubation with PKC or MEK1/2 inhibitors and ZEB siRNA silencing. CONCLUSIONS/SIGNIFICANCE: Despite activation of ERK1/2 and PKC by hyperglycemia, a distinct pool of PKCs and ERK1/2 is involved in regulation of Na,K-ATPase expression and activity by C-peptide. Most likely C-peptide stimulates sodium pump expression via activation of ZEB, a transcription

  3. Late radiation damage in bone, bone marrow and brain vasculature, with particular emphasis upon fractionation models

    X-ray induced changes in rat and human bone and bone marrow vasculature and in rat brain vasculature were measured as a function of time after irradiation and absorbed dose. The absorbed dose in the organ varied from 5 to 25 Gy for single dose irradiations and from 19 to 58 Gy for fractionated irradiations.The number of fractions varied from 3 to 10 for the rats and from 12 to 25 for the human. Blood flow changes were measured using an ''1''2''5I antipyrine or ''8''6RbCl extraction technique. The red blood cell (RBC) volume was examined by ''5''1Cr labelled red cells. Different fractionation models have been compared. Radiation induced reduction of bone and bone marrow blood flow were both time and dose dependent. Reduced blood flow 3 months after irradiation would seem to be an important factor in the subsequent atrophy of bones. With a single dose of 10 Gy the bone marrow blood flow returned to the control level by 7 months after irradiation. In the irradiated bone the RBC volume was about same as that in the control side but in bone marrow the reduction was from 32 to 59%. The dose levels predicted by the nominal standard dose (NSD) formula produced about the same damage to the rat femur seven months after irradiation when the extraction of ''8''6Rb chloride and the dry weight were concerned as the end points. However, the results suggest that the NSB formula underestimates the late radiation damage in bone marrow when a small number of large fractions are used. In the irradiated brains of the rats the blood flow was on average 20.4% higher compared to that in the control group. There was no significant difference in brain blood flow between different fractionation schemes. The value of 0.42 for the exponent of N corresponds to the average value for central nervous system tolerance in the literature. The model used may be sufficiently accurate for clinical work provided the treatment schemes used do not depart too radically from standard practice

  4. Effect of osmolarity on potassium transport in isolated cerebral microvessels

    Potassium transport in microvessels isolated from rat brain by a technique involving density gradient centrifugation was studied in HEPES buffer solutions of varying osmolarity from 200 to 420 mosmols, containing different concentration of sodium chloride, choline chloride, or sodium nitrate. The flux of 86Rb into and out of the endothelial cells was estimated. Potassium influx was very sensitive to the osmolarity of the medium. Ouabain-insensitive K-component was reduced in hypotonic medium and was increased in medium made hypertonic with sodium chloride or mannitol. Choline chloride replacement caused a large reduction in K influx. Potassium influx was significant decrease when nitrate is substituted for chloride ion in isotonic and hypertonic media, whereas a slight decrease was found in hypotonic medium. The decrease of K influx in the ion-replacement medium is due to a decrement of the ouabain-insensitive component. Potassium efflux was unchanged in hypotonic medium but was somewhat reduced in hypertonic medium. The marked effect of medium osmolarity of K fluxes suggests that these fluxes may be responsible for the volume regulatory K movements. The possible mechanism of changes of K flux under anisotonic media is also discussed

  5. Effects of radiosensitising agent nicotinamide on relative tissue perfusion and kidney junction in C3H mice

    Nicotinamide is an effective radiosensitiser of murine tumours, functioning by improving tumour perfusion by decreasing the proportion of intermittently closed capillaries. The effect of nicotinamide on relative tissue perfusion of RIF-1 tumour and normal skin, muscle, lung, liver, kidney and spleen were investigated using the 86Rb extraction technique. A dose of 1000 mg/kg was shown to have transient effects on tumour, skin and lung perfusion but to have sustained effects on muscle (a drop to 80% of control), liver, kidney and spleen (with increased ranging from 165% to 280% of control) from 0.5 to 4 h after treatment i.e. during the period of maximum radiosensitisation. These increases were evident at doses as low as 100 mg/kg. The data suggest that the radiosensitisation induced by nicotinamide in the mouse may be associated with these perfusion changes. Nicotinamide was also shown to have a substantial inhibitory effect on renal function, inhibiting 51CrEDTA clearance by a factor (± 2 SE) of 2.56 ± 0.19 and 125I-iodohippurate clearance by a factor of 2.07 ± 0.45 at 1000 mg/kg. These effects were shown to be dose-related, and to be evident at doses from 400 mg/kg upwards. This suggests that nicotinamide potentiation of co-administered cytotoxic agents may be mediated by reduced renal clearance of the cytotoxic drug, thus increasing the plasma half-life. (author)

  6. Altered erythrocyte Na-K pump in anorectic patients

    The status of the erythrocyte sodium pump was evaluated in a group of patients suffering from anorexia nervosa and a group of healthy female control subjects. Anorectic patients showed significantly higher mean values of digoxin-binding sites/cell (ie, the number of Na-K-ATPase units) with respect to control subjects while no differences were found in the specific 86Rb uptake (which reflects the Na-K-ATPase activity) between the two groups. A significant correlation was found between relative weight and the number of Na-K-ATPase pump units (r = -0.66; P less than 0.0001). Anorectic patients showed lower serum T3 concentrations (71.3 +/- 53 ng/dL) with respect to control subjects (100.8 +/- 4.7 ng/dL; P less than 0.0005) and a significant negative correlation between T3 levels and the number of pump units (r = -0.52; P less than 0.003) was found. This study therefore shows that the erythrocyte Na-K pump may be altered in several anorectic patients. The authors suggest that this feature could be interrelated with the degree of underweight and/or malnutrition

  7. Nuclear techniques for determining biomass production, evaporation and transpiration, root development and nutritional value

    From the Institute of Radiation Botany, Hanover, some nuclear methods are presented which could be of assistance to the plant breeders in selecting for positive plant characters. Several methods have been developed for the continuous determination of biomass by means of gamma-absorption measurements in single plants as well as in experimental field plots. The response of plant growth to environmental conditions such as fertilization, irrigation, and day length, dependent on genetic parameters can easily be followed by these techniques. Primarily for the investigation of water vapour movement in soils and between soil and atmosphere under conditions of temperature inversions, a technique has been worked out using 3H-labelled water and water vapour. The inclusion of plants in this system will allow the determination of water balance under varying environmental conditions. An autoradiographic method has been applied using 86Rb as trace element mainly for the measurement of root distribution of trees (apple, coffee). Finally, a sequence of analytical steps are described that have been developed and used in Hanover for the selection for protein amount and quality in crop plants. Though not all of these steps include nuclear methods, the application of tracer techniques in this and other screening sequences is an invaluable help for breeders and analysts. (author)

  8. Role of cytoskeleton network in anisosmotic volume changes of intact and permeabilized A549 cells.

    Platonova, Alexandra; Ponomarchuk, Olga; Boudreault, Francis; Kapilevich, Leonid V; Maksimov, Georgy V; Grygorczyk, Ryszard; Orlov, Sergei N

    2015-10-01

    Recently we found that cytoplasm of permeabilized mammalian cells behaves as a hydrogel displaying intrinsic osmosensitivity. This study examined the role of microfilaments and microtubules in the regulation of hydrogel osmosensitivity, volume-sensitive ion transporters, and their contribution to volume modulation of intact cells. We found that intact and digitonin-permeabilized A549 cells displayed similar rate of shrinkage triggered by hyperosmotic medium. It was significantly slowed-down in both cell preparations after disruption of actin microfilaments by cytochalasin B, suggesting that rapid water release by intact cytoplasmic hydrogel contributes to hyperosmotic shrinkage. In hyposmotic swelling experiments, disruption of microtubules by vinblastine attenuated the maximal amplitude of swelling in intact cells and completely abolished it in permeabilized cells. The swelling of intact cells also triggered ~10-fold elevation of furosemide-resistant (86)Rb+ (K+) permeability and the regulatory volume decrease (RVD), both of which were abolished by Ba2+. Interestingly, RVD and K+ permeability remained unaffected in cytocholasin/vinblastine treated cells demonstrating that cytoskeleton disruption has no direct impact on Ba2+-sensitive K+-channels involved in RVD. Our results show, for the first time, that the cytoskeleton network contributes directly to passive cell volume adjustments in anisosmotic media via the modulation of the water retained by the cytoplasmic hydrogel. PMID:26171817

  9. The physiological significance of HKT1, a Na+ - coupled high affinity K+ transporter in 'Triticum aestivum'

    Full text: Several mechanisms for high affinity K+ uptake by higher plants have been proposed:-an ATP-energised K:+ pump, a K+/H+ antiport and a H+coupled carrier. Recently, a Na+--coupled high affinity K+ transporter, HKT1, was isolated from wheat roots. Whilst Na+K+ symports have been described in charophyte algae, the cloning of HKT1 from wheat is the first, evidence that this type d transport mechanism may function in higher plants. Is the activity of HKT1 an important mechanism involved in K+ acquisition by wheat? The aim of this study was to assess the physiological significance of Na+- coupled high affinity K+ uptake in T. aestivum. To determine whether HKT1 plays a significant role in wheat growth, we measured the dry weights and ion content of plants grown in a range of [K+], with and without Na+. To directly assess the activity of Na+- coupled K+ transport, 86Rb+ and 22Na+ flux analyses were performed on the elongation zones and whole roots of intact seedlings, expressing a high affinity K+ uptake system. The results of these growth and tracer flux studies will be discussed in relation to the expression of the gene encoding HKT1 in T. aestivum

  10. Effect of dietary sodium on the Na-K ATPase inhibitor in patients with essential hypertension

    To study the circulating humoral factor modifying transmembrane sodium transport, plasma was obtained from 12 patients with essential hypertension (EH) fed a high sodium diet (NaCl 15 to 17 g/d) for seven days and thereafter a low sodium diet (NaCl 2 to 3 g/d) for seven days. Ouabain-sensitive 86Rb+ influx into the red blood cells (RBC) obtained from a healthy subject, and incubated with the plasma obtained during the high sodium diet was significantly lower than that incubated with the plasma obtained during the low sodium diet (3.74 +/- 0.26 v 3.97 +/- 0.30 nmol/10(8) cells, P less than .05). The changes in mean blood pressure from the high to low sodium diet showed a significant positive correlation with the changes in the ouabain-sensitive Rb influx into RBC in the plasma from the high to low sodium diet. These results suggest that a humoral factor modifying the sodium pump might be altered by sodium balance in EH, especially in salt-sensitive hypertension

  11. Innovations in isotope techniques to enhance the evaluation and management of nutrient sources

    The increasing world population and the need to produce more food is putting increasing pressures on soil and water resources. Increasingly, studies of interactions between nutrients rather than single nutrient studies are becoming important as systems intensify and a wider range of nutrients is added. The incorporation of isotopes into these studies will greatly assist in understanding the driving forces that determine system productivity and sustainability. Studies of N dynamics have been greatly assisted by the use of the stable 15N, and studies of water, other nutrients, and C have also been assisted by the use of radioactive isotopes such as 3H, 14C, 32P, 35S and 86Rb. However, increasing restrictions on the use of radioactive substances are beginning to severely limit their availability for such studies. Stable isotopes such as 13C, 15N and 34S offer the prospect of replacing radioactive isotopes, or of their being used in combination with radioactive isotopes, to minimize the perceived risks and/or to allow the tracing of two components in the system. The innovative use of isotopes in plant-nutrient studies utilizing direct labelling with stable isotopes, multiple direct labelling with stable and/or radioactive isotopes and/or utilizing natural abundance, reverse dilution, or a combination of direct labelling and reverse dilution, are presented. (author)

  12. Amastigotes of Trypanosoma cruzi escape destruction by the terminal complement components

    We studied the effect of complement on two life cycle stages of the protozoan parasite Trypanosoma cruzi: epimastigotes, found in the insect vector, and amastigotes, found in the mammalian host. We found that while both stages activate vigorously the alternative pathway, only epimastigotes are destroyed. The amounts of C3 and C5b-7 deposited on the amastigotes were similar to those bound to the much larger epimastigotes. Binding of C9 to amastigotes was four to six times less than binding to epimastigotes, resulting in a lower C9/C5b-7 ratio. Although a fairly large amount of C9 bound stably to amastigotes, no functional channels were formed as measured by release of incorporated 86Rb. The bound C9 had the characteristic properties of poly-C9, that is, it expressed a neo-antigen unique to poly-C9, and migrated in SDS-PAGE with an apparent Mr greater than 10(5). The poly-C9 was removed from the surface of amastigotes by treatment with trypsin, indicating that it was not inserted in the lipid bilayer. Modification of amastigote surface by pronase treatment rendered the parasites susceptible to complement attack. These results suggest that amastigotes have a surface protein that binds to the C5b-9 complex and inhibits membrane insertion, thus protecting the parasites from complement-mediated lysis

  13. Nuclear Data Sheets for A = 86

    Negret, Alexandru; Singh, Balraj

    2015-02-15

    The experimental nuclear spectroscopic data for known nuclides of mass number 86 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc) have been evaluated and presented together with Adopted properties for levels and γ rays. New high-spin data are available for {sup 86}Se, {sup 86}Br, {sup 86}Kr, {sup 86}Sr, {sup 86}Y, {sup 86}Zr and {sup 86}Mo; and lifetime data for high-spin states in {sup 86}Y and {sup 86}Zr. No significant new data since the 2001 NDS for A=86 have been reported for {sup 86}Rb and {sup 86}Nb. No data are yet available for excited states in {sup 86}Ga and {sup 86}As. The decay scheme of radioactive {sup 86}Ge is unknown, while those for {sup 86}Ga, {sup 86}As, 47.4 min isomer of {sup 86}Y, {sup 86}Nb and {sup 86}Tc are deemed as incomplete. Isomerism in {sup 86}Nb remains unconfirmed. This work supersedes the data presented in the previous NDS evaluation of A=86 published by 2001Si43.

  14. Membrane potential and surface potential in mitochondria: uptake and binding of lipophilic cations.

    Rottenberg, H

    1984-01-01

    The uptake and binding of the lipophilic cations ethidium+, tetraphenylphosphonium+ (TPP+), triphenylmethylphosphonium+ (TPMP+), and tetraphenylarsonium+ (TPA+) in rat liver mitochondria and submitochondrial particles were investigated. The effects of membrane potential, surface potentials and cation concentration on the uptake and binding were elucidated. The accumulation of these cations by mitochondria is described by an uptake and binding to the matrix face of the inner membrane in addition to the binding to the cytosolic face of the inner membrane. The apparent partition coefficients between the external medium and the cytosolic surface of the inner membrane (K'o) and the internal matrix volume and matrix face of the inner membrane (K'i) were determined and were utilized to estimate the membrane potential delta psi from the cation accumulation factor Rc according to the relation delta psi = RT/ZF ln [(RcVo - K'o)/(Vi + K'i)] where Vo and Vi are the volume of the external medium and the mitochondrial matrix, respectively, and Rc is the ratio of the cation content of the mitochondria and the medium. The values of delta psi estimated from this equation are in remarkably good agreement with those estimated from the distribution of 86Rb in the presence of valinomycin. The results are discussed in relation to studies in which the membrane potential in mitochondria and bacterial cells was estimated from the distribution of lipophilic cations. PMID:6492133

  15. Measurement of the hyperfine splitting of {sup 133}Cs atoms in superfluid helium

    Imamura, K., E-mail: kimamura@riken.jp [RIKEN Nishina Center (Japan); Furukawa, T. [Tokyo Metropolitan University, Department of Physics (Japan); Yang, X. F. [Peking University, School of Physics (China); Mitsuya, Y. [Meiji University, Department of Physics (Japan); Fujita, T. [Osaka University, Department of Physics (Japan); Hayasaka, M. [Tokyo Gakugei University, Department of Physics (Japan); Kobayashi, T. [RIKEN Center for Advanced Photonics (Japan); Hatakeyama, A. [Tokyo University of Agriculture and Technology, Department of Applied Physics (Japan); Ueno, H. [RIKEN Nishina Center (Japan); Odashima, H. [Meiji University, Department of Physics (Japan); Matsuo, Y. [Hosei University, Department of Advanced Sciences (Japan)

    2015-04-15

    We have been developing a new nuclear laser spectroscopy method named “OROCHI” (Optical RI-atom Observation in Condensed Helium as Ion-catcher). OROCHI utilizes superfluid helium (He II) not only as an efficient stopping medium of highly energetic ions but also as a host matrix of in-situ atomic laser spectroscopy. Using these characteristic of He II, we produce atomic spin polarization and measure Zeeman and hyperfine structure (HFS) splitting using laser-RF (radio frequency) / MW (microwave) double resonance method. From the measured energy splittings, we can deduce nuclear spins and moments. So far, we have conducted a series of experiments using both stable ({sup 85,87}Rb, {sup 133}Cs, {sup 197}Au, {sup 107,109}Ag) and unstable isotopes ({sup 84,86}Rb) to confirm the feasibility of OROCHI method, especially observing Zeeman resonance and determining nuclear spins. The measurement of HFS splitting of atoms introduced into He II is indispensable to clarify the nuclear properties by deducing nuclear moments as well as the study of nuclear spins. For this purpose, we perform a precision measurement of HFS of {sup 133}Cs atoms immersed in He II using laser ablation technique. In this paper, we describe the result of the experiment.

  16. Limits on the release of Rb isotopes from a zeolite based 83mKr calibration source for the XENON project

    Hannen, V; Arneodo, F; Baudis, L; Beck, M; Bokeloh, K; Ferella, A D; Giboni, K; Lang, R F; Lebeda, O; Ortjohann, H -W; Schumann, M; Spalek, A; Venos, D; Weinheimer, C

    2011-01-01

    The isomer 83mKr with its half-life of 1.83 h is an ideal calibration source for a liquid noble gas dark matter experiment like the XENON project. However, the risk of contamination of the detector with traces of the much longer lived mother isotop 83Rb (86.2 d half-life) has to be ruled out. In this work the release of 83Rb atoms from a 1.8 MBq 83Rb source embedded in zeolite beads has been investigated. To do so, a cryogenic trap has been connected to the source for about 10 days, after which it was removed and probed for the strongest 83Rb gamma-rays with an ultra-sensitive Germanium detector. No signal has been found. The corresponding upper limit on the released 83Rb activity means that the investigated type of source can be used in the XENON project and similar low-background experiments as 83mKr generator without a significant risk of contaminating the detector. The measurements also allow to set upper limits on the possible release of the isotopes 84Rb and 86Rb, traces of which were created alongside ...

  17. Upper limit of 83Rb release into the gas phase from a 83mKr calibration source for the XENON project

    The isomer 83mKr with its half-life of 1.83 h is an ideal calibration source for a liquid noble gas dark matter experiment like the XENON project. For such a low counting experiment the possibility that traces of the much longer living mother isotop 83Rb (t1/2 = 86.2 d) contaminate the detector must be avoided. In this work the 83Rb release of a 1.8 MBq strong 83Rb source embedded in zeolite spheres has been investigated by searching for the characteristic 83Rb γ lines with the ultra-sensitive germanium detector Gator at LNGS after collecting a possible 83Rb release in a cryogenic trap for about 10 days. No signal has been found. The corresponding upper limit for the 83Rb release of 200μBq means, that such a 83Rb source as 83mKr generator can be used at the XENON project as well as for the KATRIN experiment. % without the danger of contaminating the detector with 83Rb. The germanium detector also allowed to set upper limits on the possible release of the isotopes 84Rb and 86Rb, which were produced during the 83Rb production at the Rez cyclotron to some amount.

  18. Insulin regulation of Na/K pump activity in rat hepatoma cells

    Insulin rapidly increases Na/K pump activity in HTC rat hepatoma cells in tissue culture, as measured by the ouabain-sensitive influx of the potassium analogue 86Rb+. Increased influx is observed within minutes and is maximal (70% above control) within 1-2 h. The effect appears to be mediated by the insulin receptors, as: the concentration dependence on insulin is identical to that for insulin induction of tyrosine aminotransferase and stimulation of 2-aminoisobutyric acid transport, proinsulin is 6% as potent as insulin, and the effect is blocked by anti-receptor antibodies. The early stimulation of potassium influx is not blocked by cycloheximide and is not associated with an increased number of pump sites as measured by 3H-ouabain binding. The insulin effect is blocked by amiloride, which blocks sodium influx, and is mimicked by the sodium ionophore monensin, which increases sodium influx and intracellular accumulation. Insulin also rapidly increases the initial rate of 22Na+ influx, suggesting that insulin may enhance Na/K pump activity, in part, by increasing intracellular sodium concentration. Incubation of HTC cells with insulin for 24 h causes complete unresponsiveness to the insulin induction of transaminase and stimulation of amino acid transport, a phenomenon mediated by postbinding mechanisms. In contrast, similar incubation with insulin does not cause unresponsiveness to the insulin stimulation of Na/K pump activity. Therefore, the site of regulation of responsiveness to insulin must be distal to, or separate from, those events causing stimulation of ion fluxes

  19. Insulin regulation of Na/K pump activity in rat hepatoma cells

    Gelehrter, T.D.; Shreve, P.D.; Dilworth, V.M.

    1984-05-01

    Insulin rapidly increases Na/K pump activity in HTC rat hepatoma cells in tissue culture, as measured by the ouabain-sensitive influx of the potassium analogue 86Rb+. Increased influx is observed within minutes and is maximal (70% above control) within 1-2 h. The effect appears to be mediated by the insulin receptors, as: the concentration dependence on insulin is identical to that for insulin induction of tyrosine aminotransferase and stimulation of 2-aminoisobutyric acid transport, proinsulin is 6% as potent as insulin, and the effect is blocked by anti-receptor antibodies. The early stimulation of potassium influx is not blocked by cycloheximide and is not associated with an increased number of pump sites as measured by /sup 3/H-ouabain binding. The insulin effect is blocked by amiloride, which blocks sodium influx, and is mimicked by the sodium ionophore monensin, which increases sodium influx and intracellular accumulation. Insulin also rapidly increases the initial rate of /sup 22/Na+ influx, suggesting that insulin may enhance Na/K pump activity, in part, by increasing intracellular sodium concentration. Incubation of HTC cells with insulin for 24 h causes complete unresponsiveness to the insulin induction of transaminase and stimulation of amino acid transport, a phenomenon mediated by postbinding mechanisms. In contrast, similar incubation with insulin does not cause unresponsiveness to the insulin stimulation of Na/K pump activity. Therefore, the site of regulation of responsiveness to insulin must be distal to, or separate from, those events causing stimulation of ion fluxes.

  20. Limulus test for pyrogens and radiometric sterility tests on radiopharmaceuticals. Part of a coordinated programme

    Sterility testing of radiopharmaceuticals prepared at BARC were carried out using the radiometric technique (Radiometric detection of the metabolic product 14Co2). Batches of different radiopharmaceuticals were tested for pyrogen using the limulus lysate method and the results were compared with the rabbit method. The results of sterility test on 202 batches of 19 different radiopharmaceuticals show that the radiometric method can be used for sterility testing of radiopharmaceuticals labelled with 35S, 51Cr, 57Co, 59Fe, 82Br, 86Rb, sup(99m)Tc, sup(113m)In, 125I and 169Yb. The radiometric test proves to be more rapid than the conventional one for the sterility testing of such radiopharmaceuticals. Detection time is between 6-21 hours. In the case of 131I-labelled radiopharmaceuticals and in the case of chlormerodrin-Hg-203, it was found an interference due to volatile species (sup(131m)Xe in the case of 131I and some volatile mercury form in the case of chlormerodrin). In these cases it would be possible to carry out the radiometric sterility test after separation of the microorganisms from the radioactive material (by filtration). The limulus lysate method can be employed for control of various pyrogen-prone raw materials and radiopharmaceuticals. Such method is the only method at present available for detecting the low level pyrogen contamination in intrathecal injections. The limulus test is more rapid than the rabbit test

  1. Effect of ADH on rubidium transport in isolated perfused rat cortical collecting tubules

    Unidirectional fluxes of 86Rb+ were measured as an indicator of potassium transport in isolated rat cortical collecting tubules perfused and bathed at 38 degrees C with isotonic solutions in which Rb+ replaced K+. Under control conditions the lumen-to-bath flux (Jl----b) was significantly less than the bath-to-lumen flux (Jb----l), indicating net Rb+ secretion. Net secretion increased approximately 180% after addition of 100 microU/ml of arginine vasopressin (ADH) to the bathing solution, due to a rapid and reversible increase in Jb----l from 4.6 +/- 0.8 to 9.0 +/- 1.9 pmol X min-1 X mm-1 with no significant change in Jl----b. The ADH effect was completely inhibited by 2 mM luminal Ba2+. The average transepithelial voltage (Ve) was not significantly different from zero in the control period but became lumen negative (-5 to -10 mV) after ADH. With 10(-5) M amiloride in the lumen Ve was lumen positive (+2 to +4 mV) and was unaltered by ADH or Ba2+, yet ADH produced a significant but attentuated increase in Jb----l with no change in Jl----b. The results indicate that ADH augments net K+ secretion either by an increase in the Ba2+-sensitive conductance of the apical membrane or by an increase in the electrochemical potential driving force for net Rb+ secretion through this pathway

  2. Stimulus-secretion coupling of arginine-induced insulin release: Comparison with histidine-induced insulin release

    L-Histidine, when tested at a 10-mM concentration, caused a rapid and sustained stimulation of insulin release from rat islets exposed to either D-glucose (7.0 or 8.3 mM) or L-leucine (10.0 mM). The stimulation of insulin release could not be ascribed to an increase in oxygen uptake, to the generation of histamine from L-histidine, or to its participation in a transglutaminase-catalyzed reaction. Like other cationic amino acids, however, L-histidine rapidly accumulated in islet cells, increased 86Rb outflow from prelabeled islets perifused in the presence or absence of extracellular Ca2+, and stimulated the entry of Ca2+ into islet cells. Yet, the amount of exogenous L-histidine present in the islet cells with a positively charged side chain was estimated to be below the threshold value required for stimulation of insulin release by fully ionized cationic amino acids, such as L-arginine. Hence, the present findings argue against the view that the insulinotropic action of cationic amino acids is solely attributable to the accumulation of these positively charged molecules inside the islet B cell with subsequent depolarization of the plasma membrane

  3. Altered erythrocyte Na-K pump in anorectic patients

    Pasquali, R.; Strocchi, E.; Malini, P.; Casimirri, F.; Ambrosioni, E.; Melchionda, N.; Labo, G.

    1985-07-01

    The status of the erythrocyte sodium pump was evaluated in a group of patients suffering from anorexia nervosa and a group of healthy female control subjects. Anorectic patients showed significantly higher mean values of digoxin-binding sites/cell (ie, the number of Na-K-ATPase units) with respect to control subjects while no differences were found in the specific /sup 86/Rb uptake (which reflects the Na-K-ATPase activity) between the two groups. A significant correlation was found between relative weight and the number of Na-K-ATPase pump units (r = -0.66; P less than 0.0001). Anorectic patients showed lower serum T3 concentrations (71.3 +/- 53 ng/dL) with respect to control subjects (100.8 +/- 4.7 ng/dL; P less than 0.0005) and a significant negative correlation between T3 levels and the number of pump units (r = -0.52; P less than 0.003) was found. This study therefore shows that the erythrocyte Na-K pump may be altered in several anorectic patients. The authors suggest that this feature could be interrelated with the degree of underweight and/or malnutrition.

  4. Pancreatic blood flow in experimental acute pancreatitis

    The etiology and pathogenesis of acute necrotizing hemorrhagic pancreatitis remain controversial. Recent work has suggested that an early fall in pancreatic blood flow, causing ischemia, may be the initiating factor. Using an established rat model of hemorrhagic pancreatitis and the fractional indicator distribution technique with 86RbCl, pancreatic blood flow and tissue perfusion have been measured at various times in the condition. Six groups of ten rats were studied: control sham operation and pancreatitis groups were sacrificed at 1, 6, and 24 hr. Pancreatic blood flow (% of cardiac output) and perfusion (blood flow/g tissue) were measured. Blood flow was increased by a maximum of 53% at 1 hr (P less than 0.001) and remained elevated for 24 hr, and perfusion was increased by a maximum of 70% (P less than 0.001) at 1 hr and remained elevated at 6 hr. Pancreatic perfusion declines after 6 hr due to increasing gland edema. The results demonstrate a significant increase in pancreatic blood flow and perfusion in experimentally induced acute pancreatitis, suggesting a primary inflammatory response, and refute the ischemic etiological theory

  5. Theoretical Study of the Molecular and Electronic Structures of CPDT-TCNQ and Its Difluoro and Dimethyl Derivatives

    GONG Zhi-Jun; LI Qian-Shu

    2006-01-01

    CPDT-TCNQ and its derivatives are good candidates for charge-transfer acceptors.In this work, the electronic ground and excited states of CPDT-TCNQ as well as its difluoro and dimethyl derivatives are studied. The ground state optimized structures and energies were obtained using a restricted (closed-shell) density functional theory (DFT) as approximated by the various hybrid functionals (RB3LYP, RB3P86, RB3PW91). The 6-31G** and 6-31+G** basis sets were employed in calculations. All derivatives are planar and exhibit a quinoid structure in their electronic ground states. The energy and oscillator strength of the first 15 singlet-singlet electronic transitions have been investigated by applying the time-dependent density functional theory (TD-DFT) approximations to the correspondingly optimized ground state geometries. The results show the strongest absorption in electronic spectra of molecules due to the HOMO-LUMO electronic transition of the thiophene backbone.

  6. Measurement of the hyperfine splitting of 133Cs atoms in superfluid helium

    We have been developing a new nuclear laser spectroscopy method named “OROCHI” (Optical RI-atom Observation in Condensed Helium as Ion-catcher). OROCHI utilizes superfluid helium (He II) not only as an efficient stopping medium of highly energetic ions but also as a host matrix of in-situ atomic laser spectroscopy. Using these characteristic of He II, we produce atomic spin polarization and measure Zeeman and hyperfine structure (HFS) splitting using laser-RF (radio frequency) / MW (microwave) double resonance method. From the measured energy splittings, we can deduce nuclear spins and moments. So far, we have conducted a series of experiments using both stable (85,87Rb, 133Cs, 197Au, 107,109Ag) and unstable isotopes (84,86Rb) to confirm the feasibility of OROCHI method, especially observing Zeeman resonance and determining nuclear spins. The measurement of HFS splitting of atoms introduced into He II is indispensable to clarify the nuclear properties by deducing nuclear moments as well as the study of nuclear spins. For this purpose, we perform a precision measurement of HFS of 133Cs atoms immersed in He II using laser ablation technique. In this paper, we describe the result of the experiment

  7. Intestinal circulation during inhalation anesthesia

    This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86Rb and 9-microns spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001). Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO2) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines

  8. Energy-linked potassium influx as related to cell potential in corn roots

    Cell potentials and K+ (86Rb) influx were determined for corn roots over a wide range of external K+ activity (K0) under control, anoxic, and uncoupled conditions. The data were analyzed using Goldman theory for the contribution of passive influx to total influx. For anoxic and uncoupled roots the K+ influx shows the functional relationship with K0 predicted with constant passive permeability, although K+ permeability in uncoupled roots is about twice that of anoxic roots. In control roots the equation fails to describe K+ infux at low K0, but does so at high K0, with a gradual transition over the region where the electrical potential becomes equal to the equilibrium potential for K+ (psi = E/sub K/). In the low K0 range, where net K+ infux is energetically uphill, participation of an energy-linked K+ carrier is indicated. In the high K0 range, K+ influx becomes passive down the electrical gradient established by the cell potential. Since the cell potential includes a substantial electrogenic component, anoxia or uncoupling reduces passive influx

  9. Biliary excretion and enterohepatic recycling of proscillaridin A after oral administration to man

    A single oral dose of proscillaridin A (1.0-1.5 mg) was given to six patients with T-tube drainage of the common bile duct, and simultaneous samples of bile and plasma were collected at various times during the following 24 hours. Glycoside activity was assayed by the 86Rb-uptake inhibition technique. Peak activities in plasma (mean 0.80 ng/ml) were attained after 0.5-2h, and in bile (mean 6.9ng/ml) after 1-4h. Subsequently, proscillaridin activity in bile was less than 5ng/ml for the remainder of the sampling period, and 10-100 times higher than that in plasma. Bile samples treated with β-glucuronidase and sulphatase showed 100-200 fold increase in glycoside activity. Deconjugation was also produced by treatment with enteric contents. The results suggest that conjugation of unchanged proscillaridin is a major metabolic route. After excretion in the bile, the conjugates may be split in the intestine and reabsorbed as active glycoside. (orig.)

  10. Ionic and secretory response of pancreatic islet cells to minoxidil sulfate

    Antoine, M.H.; Hermann, M.; Herchuelz, A.; Lebrun, P. (Laboratory of Pharmacology, Brussels Free University School of Medicine (Belgium))

    1991-07-01

    Minoxidil sulfate is an antihypertensive agent belonging to the new class of vasodilators, the K+ channel openers. The present study was undertaken to characterize the effects of minoxidil sulfate on ionic and secretory events in rat pancreatic islets. The drug unexpectedly provoked a concentration-dependent decrease in 86Rb outflow. This inhibitory effect was reduced in a concentration-dependent manner by glucose and tolbutamide. Minoxidil sulfate did not affect 45Ca outflow from islets perfused in the presence of extracellular Ca++ and absence or presence of glucose. However, in islets exposed to a medium deprived of extracellular Ca++, the drug provoked a rise in 45Ca outflow. Whether in the absence or presence of extracellular Ca++, minoxidil sulfate increased the cytosolic free Ca++ concentration of islet cells. Lastly, minoxidil sulfate increased the release of insulin from glucose-stimulated pancreatic islets. These results suggest that minoxidil sulfate reduces the activity of the ATP-sensitive K+ channels and promotes an intracellular translocation of Ca++. The latter change might account for the effect of the drug on the insulin-releasing process. However, the secretory response to minoxidil sulfate could also be mediated, at least in part, by a modest Ca++ entry.

  11. Phorbol ester-induced protein secretion in rat parotid gland. Relationship to the role of inositol lipid breakdown and protein kinase C activation in stimulus-secretion coupling

    Putney, J.W. Jr.; McKinney, J.S.; Aub, D.L.; Leslie, B.A.

    1984-09-01

    When added to rat parotid gland slices incubated in vitro, 4 alpha-phorbol-dibutyrate (PDBu) induced a dose-dependent increase in protein secretion, but did not affect membrane permeability to K+ (as determined by /sup 86/Rb efflux). The response to PDBu was unaffected by the removal of extracellular Ca2+ and was not markedly potentiated by incubation with the phosphodiesterase inhibitor, methylisobutylxanthine. PDBu did not activate phospholipase C breakdown of inositol lipids as shown by a failure to increase formation of soluble inositol phosphates. When applied in combination with the Ca2+ ionophore, ionomycin, a secretory rate was obtained that was greater than the predicted sum of rates obtained when the two drugs were given alone. These results, when taken with the reported results of others, are consistent with an action of PDBu in activating protein kinase C and suggest that this enzyme plays an important role in the pathway linking receptor activation to protein secretion, but not K+ flux, in the parotid gland.

  12. A simple assay for agonist-regulated Cl and K conductances in salt-secreting epithelial cells

    Venglarik, C.J.; Bridges, R.J.; Frizzell, R.A. (Univ. of Alabama, Birmingham (USA))

    1990-08-01

    We developed a convenient flux assay that permits simultaneous measurement of Cl and K conductance pathways in Cl-secreting epithelial cells. Monolayers of the colonic tumor cell line T84 were preloaded with 125I and 86Rb, and isotope effluxes were monitored by a sample-replace procedure. The adenosine 3',5'-cyclic monophosphate (cAMP)-mediated agonists forskolin and prostaglandin E2 increased I efflux with little effect on Rb efflux, whereas the Ca-mediated agonists ionomycin, A23187, and carbachol increased both I and Rb effluxes. Simultaneous determinations of I and Cl or Rb and K effluxes indicated that I and Rb provide good measures of the effluxes of Cl and K, respectively. Forskolin- and ionomycin-stimulated I effluxes were inhibited by the Cl-channel blockers diphenylamine-2-dicarboxylate (DPC), 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB), and 2-(cyclopentyl-6,7-dichloro-2,3-dihydro-2-methyl-1-oxo-1H- inden-5-yl-oxy)acetic acid (IAA-94) and by high external K. The Rb efflux evoked by ionomycin was inhibited by the K-channel blockers Ba and charybdotoxin. These findings suggest that I and Rb effluxes provide qualitative estimates of agonist-stimulated Cl and K conductance pathways. Thus this method can provide a simple and relatively inexpensive screening assay for Cl and K conductances in cultured cells to assess the effects of agonist, blockers, or genetic manipulations.

  13. Feasibility of the instrumental neutron activation analysis of entire archaeological pottery. Part 1: Precision of the results and radiological safety of the process

    The feasibility of the instrumental neutron activation analysis of entire pieces of archaeological pottery, using low thermal neutron fluxes, is examined. The study takes into account the chemical elements relevant for archaeological investigations, as well as the degree of accuracy required for such kind of research. It is shown that after irradiation of a typical pottery sample of about 1 kg during 45 minutes, at a thermal flux of about 109 n.cm-2.s-1, analytical signals are obtained, by gamma spectrometry, with counting statistics better than 1%, for 76As, 131Ba, 141Ce, 60Co, 134Cs, 181Hf, 140La, 24Na, 122Sb, 46Sc, 153Sm and 233Pa, whereas 51Cr, 152Eu, 42K, 86Rb, 175Yb and 65Zn can be detected with counting statistics within 1% and 2%. On the other hand, the statistics of measurement are relatively poor (orders of 3% - 10%) for 177Lu, 147Nd, 239Np, 160Tb and 181Ta. The feasibility of accomplishment reliable quantitative determinations, taking into account the complexity of the analysis of entire pieces of archaeological pottery is discussed, which involves factors such as high masses, as well as asymmetric and variable shapes. (orig.)

  14. Exogenous phospholipase C permeabilizes mammalian cells to proteins

    Mammalian cells treated with low concentrations of phospholipase C become permeable to the protein toxin alpha-sarcin. A similar permeabilization is not induced upon treatment with other lipases such as phospholipase A2, sphingomyelinase, or cholesterol esterase. Concentrations of 10 micrograms/ml alpha-sarcin almost completely blocked translation in HeLa cells treated with 0.3 U/ml phospholipase C (PL-C) for 1 h. In contrast, 200 micrograms/ml of alpha-sarcin had no effect at all on protein synthesis in untreated cells. Other macromolecules such as horseradish peroxidase and luciferase also enter into cells if they are treated with phospholipase C. This permeabilization method is fully reversible. As soon as 5 min after PL-C removal, the cells become impermeable to alpha-sarcin. Other metabolites such as uridine nucleotides are partially released after PL-C incubation, whereas the content of 86Rb+ remains at control levels, probably because the Na+/K+ ATPase activity increases

  15. Lack of interaction between digoxin and quinidine in cultured heart cells

    Previous investigations have raised the possibility that the digoxin-quinidine interaction is associated with a reduction in the positive inotropic effect of digoxin due to displacement of digoxin from cardiac as well as skeletal muscle. To circumvent some of the complexities presented by intact animal models, this interaction was investigated in cultured chick embryo ventricular cells. Quinidine, even at relatively high concentrations (10(-4)--2 x 10(-3) M), did not significantly affect positive inotropic effects of digoxin and did not protect against cellular contracture induced by toxic digoxin concentrations, despite preincubation of cells with quinidine for 60 min. The effects of digoxin on monovalent cation transport, as judged by active uptake of the K analog 86Rb, were also not altered by 10(-4) M to 2 x 10(-3) M quinidine. These data suggest that quinidine does not displace digoxin from Na, K adenosine triphosphatase binding sites in this preparation. Although these data must be extrapolated to the intact animal with caution, our findings suggest that changes in digoxin clearance are more likely of primary importance in the digoxin-quinidine interaction, and indicate that the approximately 2-fold increase in serum digoxin concentration observed after addition of quinidine would be expected to have direct effects on myocardial cells comparable with those seen with increased digoxin concentration in the absence of quinidine

  16. Development of NIRS models to predict protein and amylose content of brown rice and proximate compositions of rice bran.

    Bagchi, Torit Baran; Sharma, Srigopal; Chattopadhyay, Krishnendu

    2016-01-15

    With the escalating persuasion of economic and nutritional importance of rice grain protein and nutritional components of rice bran (RB), NIRS can be an effective tool for high throughput screening in rice breeding programme. Optimization of NIRS is prerequisite for accurate prediction of grain quality parameters. In the present study, 173 brown rice (BR) and 86 RB samples with a wide range of values were used to compare the calibration models generated by different chemometrics for grain protein (GPC) and amylose content (AC) of BR and proximate compositions (protein, crude oil, moisture, ash and fiber content) of RB. Various modified partial least square (mPLSs) models corresponding with the best mathematical treatments were identified for all components. Another set of 29 genotypes derived from the breeding programme were employed for the external validation of these calibration models. High accuracy of all these calibration and prediction models was ensured through pair t-test and correlation regression analysis between reference and predicted values. PMID:26258697

  17. Mineral cycling in a young Douglas fir forest stand

    Radiotracers for phosphorus (32P), potassium (substitute 86Rb), and calcium (45Ca) were used to follow the turnover of nutrients entering the forest floor with rainwash. Phosphorus moved readily through the forest floor to be strongly retained by the acid mineral soil. Considerable phosphorus absorbed by trees was correlated with forest-floor leachate contents and became concentrated in physiologically active tissues. Losses with litterfall and rainwash were nondetectable; this indicated high retention and internal redistribution. Rapid movement toward sinks appeared to be characteristic. In contrast, the larger amounts of calcium added were absorbed by the exchange capacity of the forest floor, with subsequent small but relatively unrestricted movement through the soil and trees. Both calcium and potassium absorption by trees was correlated with mineral-soil leachate contents. Annual potassium mobility fell between that of phosphorus and calcium and appeared to be more dependent on temperature and moisture conditions of the forest ecosystem, with potassium moving rapidly in subcycles during wet periods of the growing season

  18. The competition of Linum with Camelina for minerals. 2

    The uptake of 32P-phosphate and 86Rb through the roots into 20-day-old plants of flax (Linum usitassimum L.) and Camelina sativa (L.) Crantz was examined, both in monoculture and mixed culture. After periods of one hour the Camelina plants already taken up essentially more phosphate and rubidium ions than the Linum plants. In mixed cultures of the two species, the Linum plants absorbed less, the Camelina plants more phosphate and rubidium ions than in the respective monocultures. These differences may be explained as the consequence of a competition of the species taking up ions to a varied extent. As under the conditions of competition for sulphate ions, the Camelina plants, in spite of considerably minor root volume, proved to be the superior partner with regard to the integration of mineral substances. It can be assumed, therefore, that the smaller harvest of the flax when associated with Camelina is caused to a decisive extent by competition and not by allelopathic phenomena. (author)

  19. Combined radioactivation methods in determining trace elements

    The authors have devised a method of radioactivation analysis (RAA) for determining 32 elements by NAA, proton-activation analysis (PAA), and emission spectral analysis (ESA). Here they examine element distributions in certain plants by NAA, PAA, and DAA (deuteron activation analysis) as described elsewhere. The results are compared with those from activation analysis (AA) and ESA. The authors used five species of medicinal plant: Plantago Major L, Salvia officinalis L., Artemisia absinthium L., Alhagi Persarum, and Eremurus. They used referenced methods for preparing the samples, irradiating them in the reactor or cyclotron, and measuring the radioactivity. The γ-ray spectra for the activated samples from all the plants gave peaks representing 24Na, 42K, 56Mn, 140La, 82Br, 124Sb, 46Sc, 59Fe, 198Au, 139Ce, 153Sm, 86Rb, 65Zn, 60Co, and 147MSn. The concentrations of Fe, Sb, Sn, Zn, Rb, Co were determined when the irradiated samples have been kept for 10 days. To determine Ca, Fe, Ti, Cu, Zn, and Sr, ash disks were irradiated by proton and deuteron beams in a cyclotron, where they recorded radiation from the 48Sc, 56Co, 48V, 65Zn, 67Ga, 88Y. The conclusions are that all these plants and the parts of them accumulate the elements in different ways

  20. Cotransport of water by Na¿-K¿-2Cl¿ cotransporters expressed in Xenopus oocytes

    Zeuthen, Thomas; Macaulay, Nanna

    2012-01-01

    The NKCC1 and NKCC2 isoforms of the mammalian Na¿–K¿–2Cl¿ cotransporter were expressed in Xenopus oocytes and the relation between external ion concentration and water fluxes determined.Water fluxes were determined from changes in the oocytes volume and ion fluxes from 86Rb+ uptake. Isotonic...... increases in external K¿ concentration elicited abrupt inward water fluxes in NKCC1; the K¿ dependence obeyed one-site kinetics with a K0.5 of 7.5 mM. The water fluxes were blocked by bumetanide, had steep temperature dependence and could proceed uphill against an osmotic gradient of 20 mosmol l¿¹. A...... comparison between ion and water fluxes indicates that 460 water molecules are cotransported for each turnover of the protein. In contrast, NKCC2 did not support water fluxes.Water transport in NKCC1 induced by increases in the external osmolarity had high activation energy and was blocked by bumetanide. The...

  1. The Grimsel field tracer migration experiment. What have we achieved after a decade of intensive work?

    The Nagra/PNC field tracer migration experiment, carried out in association with PSI (Switzerland) and GSF (Germany), began in 1985 with hydrogeological characterisation of a water conducting shear zone in the granodiorite of Nagra's Grimsel Test Site (GTS, in the central Swiss Alps) and finished in the spring of 1996. The intervening decade has seen a large series of field tracer migration experiments carried out at the site, increasing in complexity from simple, non-sorbing tracers (uranin, 82Br, 123I, 3He and tritium) through various weakly sorbing tracers (22Na, 24Na, 85Sr and 86Rb) to a final, long-term experiment with strongly sorbing 137Cs. Over the last ten years, the experimental methodology has matured as has understanding of both the site and the processes influencing in situ radionuclide retardation in fractured crystalline rocks. However, this knowledge has been won only following significant investment of both effort and funds so it is appropriate to now review the returns on the investment in terms of a repository performance assessment (PA). (author)

  2. Characterization of ultraviolet light-induced ouabain-resistant mutations in Chinese hamster cells

    Ouabain-resistant mutations in Chinese hamster cells have been quantitatively characterized. The mutation frequencies were found to be induced curvilinearly with treatments of increasing doses of ultraviolet light (UV). For the range of UV doses tested (5-20 J/m2), the observed mutation frequency, Y, as a function of UV dose X, follows a curvilinear function, Y=(-28+13.37X - 1.52X2+0.08 X3).10-6. The frequencies of UV-induced mutations were directly correlated with cell survival, indicating a similar causal relationship between cell killing and mutation induction. Under the same experimental conditions, X-rays induced 6-thioguanine-, but not ouabain-, resistant mutations, UV-induced ouabain-resistant (ouasup(r)) mutants exhibit a selection disadvantage. Their phenotypic expressions are modifiable by various agents. Wild type and 16 ouasup(r) mutants were compared with respect to their sensitivity to ouabain inhibition of 86Rb uptake by whole cells. All the ouasup(r) mutants assayed are less sensitive to the drug than are wild-type cells. In the absence of ouabain, the Na+-K+-ATPase activities can be significantly higher or lower than that of the wild-type cells. (Auth.)

  3. Activity identification of peptide containing rat sodium pump α2 subunit M1-M2 extramembrane fragment in vitro%大鼠钠泵α2亚单位M1~M2膜外区多肽体外活性鉴定

    张明娟; 杨军; 强磊; 王蓉; 宋亚燔; 牛小麟

    2008-01-01

    本文旨在研究含大鼠钠泵α2亚单位M1~M2膜外区的多肽片段(peptide contmning rat sodium pump α2 subunit M1-M21extramembrane fragment,RES2衍生物)是否具有与内源性钠泵抑制因子结合以及改善钠泵α亚单位活性的作用.采用Fmoc固相合成法合成多肽(Leu-Ala-Ala-Met-Glu-Asp-Glu-Pro-Ser-Asn-Asp-Asn-Gly-Gly-Gly-Ser),产物经高效液相色谱技术纯化,并进行质谱分析.采用放射性配体.受体结合法检测其与哇巴因的结合能力,进而采用人红细胞86Rb摄取实验检测其生物学活性.结果显示,RES2衍生物与3H-哇巴因具有一定的结合能力,其平衡解离常数(Kd)为38.46 nmol/L,IC50为6.353nmol/L.RES2衍生物可以阻断哇巴因对红细胞膜Na+,K+-ATPase的抑制作用,使红细胞86Rb摄取率从38.53%上升到83.69%左右,并呈一定的剂量依赖关系.因此,RES2衍生物不仅具有体外结合活性,而且具有改善钠泵活性的生物学效应,为其成为有效的抗高血压药物提供科学依据.%In order to explore the activity of a peptide containing rat sodium pump α2 subunit M I-M2 extramembrane fragment (RES2derivative) in vitro, the peptide (Len-Ala-Ala-Met-Glu-Asp-Glu-Pro-Ser-Asn-Asp-Asn-Gly-Gly-Gly-Ser) was synthesized by pep-tide synthesizer with Fmoc method and purified by high performance liquid chromatography (HPLC). Its binding activity wasidentified by radioligand-receptor binding assay (RRA) and its bioactivity was measured by erythrocyte 86Rb uptake. The results ofsaturation binding experiment and competitive binding experiment showed that the synthesized RES2 derivative had the capability tobind to 3H-ouabain. The dissociation constant (Kd) was 38.46 nmol/L and IC50 was 6.353 nmol/L. Erythrocyte 86Rb uptake experimentshowed that the RES2 derivative blocked the inhibitory effect of ouabain on the sodium pump on erythrocyte membrane in a dose-dependent manner. The results showed that the RES2 derivative is capable of binding to ouabain and

  4. Influences of follicle-stimulating hormone, proteases, and antiproteases on permeability of the barrier generated by Sertoli cells in a two-chambered assembly

    Factors have been identified that influence the integrity of the barrier generated by Sertoli cells (SC) in culture in a two-chambered assembly. The permeability of the barrier was assessed by determining rates of equilibration of [3H]methoxyinulin or [86Rb]Cl across the Sertoli cell monolayer. The complete system consisted of a confluent monolayer of SC maintained on an extracellular matrix (Matrigel)-coated filter together with peritubular cells on the opposite side of the filter. In confirmation of previous results, levels of plasminogen activator (PA) activity secreted were increased by treatment of SC with FSH or with cAMP derivatives [(Bu)2cAMP (dbcAMP)]. PA levels in the culture medium were inversely related to times required for 50% equilibration of [3H]methoxyinulin across the SC monolayer. Thus, elevated PA levels, elicited by stimulation with FSH or dbcAMP, were associated with a decreased integrity of the barrier generated by SC preparations maintained in serum-free medium in the complete system. The increase in permeability of the barrier in SC elicited by FSH dbcAMP could be prevented, however, by the addition of various antiproteases. FSH actions on barrier function were complex. Effects of FSH that favored barrier integrity were most readily detected when proteolytic activity was inhibited. The addition of intact serum increased the integrity of the barrier, but acid-treated serum depleted of antiproteases had no such effect. We advance the hypothesis that proteases are implicated in modulation of the formation and maintenance of the seminiferous tubule barrier by SC

  5. Labeling of Pest Insects Using Radioisotopes to Study Dispersal Pattern, Migration and Estimation of Population Density

    To study insects behaviour in their habitat such as dispersal, migration and flight range, insects are needed to be labelled to trace their movement. One of the most promising labeling methodology for internal labeling is the use of radioisotopes. Radioisotopes that have been used for labeling insects are 3H, 32P, 14Ca, 45K, 35S, 59Fe, 60Co, and 14C. Insect labeling with isotopes has more advantages as compared to dyes due to isotopes used for labeling is bonded to the tissue such as 3H, 32P, 14Ca, K, 131I. Several consideration have to be taken to determine isotopes that will be used in line with the time consuming for experiments. This have to be carried out due to the phenomenon that several isotopes are toxic to insects such as 45Ca, 59Fe, 86Rb, 110Ag, 115Cd, and 131J. Precautions have to be fulfilled for insect radiolabeling which are save to insects, environment, easy to apply, materials are available and acceptable to the public. Radioisotope 32P with a correct dose is very convenience to be used in such experiments due to its relatively short half live, which is only 14.3 days. If it is an stable isotope it can be kept for a long time so the sample analyzed can be conducted convenience for long periods of time. Stable elements such as Rb can be changed to be radioisotopes by bombardment of neutrons in a nuclear reactor or accelerator. Then the element that has been activated can be identified using solid scintillation counter, multichannel analyzer or can be detected using autoradiography. (author)

  6. Dextromethorphan and its metabolite dextrorphan block alpha3beta4 neuronal nicotinic receptors.

    Hernandez, S C; Bertolino, M; Xiao, Y; Pringle, K E; Caruso, F S; Kellar, K J

    2000-06-01

    Dextromethorphan (DM), a structural analog of morphine and codeine, has been widely used as a cough suppressant for more than 40 years. DM is not itself a potent analgesic, but it has been reported to enhance analgesia produced by morphine and nonsteroidal anti-inflammatory drugs. Although DM is considered to be nonaddictive, it has been reported to reduce morphine tolerance in rats and to be useful in helping addicted subjects to withdraw from heroin. Here we studied the effects of DM on neuronal nicotinic receptors stably expressed in human embryonic kidney cells. Studies were carried out to examine the effects of DM on nicotine-stimulated whole cell currents and nicotine-stimulated (86)Rb(+) efflux. We found that both DM and its metabolite dextrorphan block nicotinic receptor function in a noncompetitive but reversible manner, suggesting that both drugs block the receptor channel. Consistent with blockade of the receptor channel, neither drug competed for the nicotinic agonist binding sites labeled by [(3)H]epibatidine. Although DM is approximately 9-fold less potent than the widely used noncompetitive nicotinic antagonist mecamylamine in blocking nicotinic receptor function, the block by DM appears to reverse more slowly than that by mecamylamine. These data indicate that DM is a useful antagonist for studying nicotinic receptor function and suggest that it might prove to be a clinically useful neuronal nicotinic receptor antagonist, possibly helpful as an aid for helping people addicted to nicotine to refrain from smoking, as well as in other conditions where blockade of neuronal nicotinic receptors would be helpful. PMID:10869398

  7. Cellular effects of beta-adrenergic and of cAMP stimulation on potassium transport in rat alveolar epithelium.

    Saumon, G; Basset, G; Bouchonnet, F; Crone, C

    1989-07-01

    Alveolar fluid absorption is greatly enhanced by cAMP and by beta-adrenergic agonists via an increase in Na+ transport. Little is known about K+ homeostasis under these circumstances. We studied K+ transport across alveolar epithelium in isolated perfused rat lungs stimulated either by dibutyryl-cAMP or isoproterenol. K+ fluxes and the apparent permeability of 86Rb across the epithelium (alveoli to plasma) were interpreted according to a model involving two types of cells, B and L, distinguished by the location of Na+-K+-ATPases (basal and luminal). Water is considered to be absorbed by B cells in a solute-coupled process energized by a basolateral Na+-K+-ATPase that is stimulated by isoproterenol and cAMP. K+ transport out of the alveoli is due to the activity of a Na+-K+-ATPase located in the apical membrane of L cells. In the present study net transport rate of K+ was -0.5 +/- 0.15 nmol/s, n = 20 (out of alveoli) in control conditions. When the epithelium was stimulated by dibutyryl-cAMP (10(-4) mol/l) net absorption of K+ reversed to net 'secretion' into alveoli (3.2 +/- 0.31 nmol/s), fluid absorption was not stimulated. K+ 'secretion' was abolished by apical Ba2+, indicating it was due to opening of apical K+ channels. Basolateral ouabain reversed net K+ 'secretion' to net absorption indicating that K+ entry into alveoli was dependent on activity of B cell basolateral Na+-K+-ATPase (masking simultaneous K+ removal by apical L cell Na+-K+-pump). When larger concentrations of dibutyryl-cAMP (10(-3) mol/l) or when isoproterenol were used to stimulate the epithelium there was a tripling of fluid absorption.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2571117

  8. Cation transport in oxidant-stressed human erythrocytes: heightened N-ethylmaleimide activation of passive K+ influx after mild peroxidation.

    Sheerin, H E; Snyder, L M; Fairbanks, G

    1989-07-24

    Normal and chronically dehydrated (hereditary xerocytosis) human red cells were subjected to mild peroxidative treatment (315 microM hydrogen peroxide (H2O2), 15 min) in the presence of azide. The subsequent expression of passive (ouabain-resistant) K+ transport activities was analyzed by measurement of 86Rb+ influx. Peroxidation of normal red cells did not affect basal K+ transport activity, but the increment in K+ influx elicited by 0.5 mM N-ethylmaleimide (NEM) was increased 3-fold. The enhanced K+ influx was chloride-dependent, but only partially inhibited by 0.1 mM furosemide. Stimulated activity declined progressively after NEM activation, but could be restored by a second NEM treatment. Prior conversion of hemoglobin to the carbonmonoxy form abolished the response to peroxide, while 200 microM butylated hydroxytoluene (BHT) exerted only partial inhibition, suggesting that the effect of H2O2 requires interaction of activated, unstable hemoglobin species with the membrane, but that lipid peroxidation is not sufficient. Peroxidation following NEM treatment also enhanced NEM activation, indicating that enhancement does not require altered NEM reactions with stimulatory or inhibitory sites. Passive K+ transport in hereditary xerocytosis red cells was not activated by NEM, with or without H2O2 pretreatment. The results demonstrate that modest peroxidative damage to red cells can heighten the activation of a transport system that is thought to be capable of mediating net K+ efflux and volume reduction in cells that express it. Models are proposed in which the effects of NEM, H2O2, cell swelling and other factors are mediated by conformational changes in a postulated subpopulation of anion channel (Band 3) molecules that bind the K+ transporter. PMID:2758051

  9. Chloride transport in a glioma cell line

    Wolpaw, E.W.

    1984-01-01

    Maintenance of the extracellular environment is a major function of central nervous system astroglia. The transport of Cl/sup -/ across the cell membrane may be an integral part of this function, since Cl/sup -/ transport has been implicated in homeostasis of cell volume, pH, and extracellular K/sup +/ concentration. The work presented here investigated Cl/sup -/ transport in the glioma cell line LRM55. Results indicate that LRM55 cells are a good model for astroglia and that these cells contain three Cl/sup -/ transporters; a Cl/sup -//HCO/sub 3//sup -/ exchanger, a K/sup +//Cl/sup -/ cotransporter, and a Cl/sup -//SO/sub 4//sup 2 -/ exchanger. Ion transport studies measured the fluxes of Cl/sup -/ (as /sup 36/Cl/sup -/), K/sup +/ (as /sup 86/Rb/sup +/), and SO/sub 4//sup 2 -/ (as /sup 35/SO/sub 4//sup 2 -/). Cl/sup -/ flux was trans-simulated by Cl/sup -/ or HCO/sub 3//sup -/ and was inhibited by SITS or furosemide. External K/sup +/ stimulated Cl/sup -/ influx and external Cl/sup -/ stimulated Rb/sup +/ influx. Furosemide, but not SITS, inhibited the K/sup +//Cl/sup -/ cotransporter. High K/sup +/ medium increased cell volume and Cl/sup -/ content. Steady-state Cl/sup -/ concentration was at least twice that predicted from passive equilibration according to the Nernst equation. SO/sub 4//sup 2 -/ flux was trans-stimulated by SO/sub 4//sup 2 -/ or by Cl/sup -/. Cl/sup -/ was a competitive inhibitor of SO/sub 4//sup 2 -/ influx, but SO/sub 4//sup 2 -/ had no detectable effect on Cl/sup -/ influx or efflux. SO/sub 4//sup 2 -/ flux was inhibited by SITS or furosemide.

  10. Effects of atrial and brain natriuretic peptides upon cyclic GMP levels, potassium transport, and receptor binding in rat astrocytes

    Beaumont, K.; Tan, P.K. (Univ. of California, San Diego, La Jolla (USA))

    1990-02-01

    The ability of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) to alter cyclic GMP levels and NaKCl cotransport in rat neocortical astrocytes was determined. At concentrations of 10(-9)-10(-6) M, rat ANP99-126 (rANF), rat ANP102-126 (auriculin B), and rat ANP103-126 (atriopeptin III) stimulated 6- to 100-fold increases in cyclic GMP levels. Porcine BNP (pBNP) and rat BNP (rBNP) were 20%-90% as effective as rANF over most of this concentration range, although 10(-6) M pBNP produced a greater effect than rANF. NaKCl cotransport as measured by bumetanide-sensitive 86Rb+ influx was not altered by exposure of astrocytes to 10(-6)M rANF, pBNP, or rBNP. Both pBNP and rBNP, as well as rat ANP103-123 (atriopeptin I) and des(gl18, ser19, gly20, leu21, gly22) ANF4-23-NH2 (C-ANF4-23) strongly competed for specific 125I-rANF binding sites in astrocyte membranes with affinities ranging from 0.03 to 0.4 nM, suggesting that virtually all binding sites measured at subnanomolar concentrations of 125I-rANF were of the ANP-C (ANF-R2) receptor subtype. These receptors are thought to serve a clearance function and may be linked to a guanylate cyclase activity that is chemically and pharmacologically distinct from that coupled to ANP-A (ANF-R1) receptors. ANP receptors on astrocytes may function in limiting the access of ANP and BNP to neurons involved in body fluid and cardiovascular regulation.

  11. Is cold labelling of human platelets with rubidium feasible?

    Full text: 111In labeling of human platelets is the methodology of choice for monitoring kinetics and abnormal deposition. permit easy visualisation by the gamma camera. Avoiding use of radionuclides may allow application in children and pregnant at the expense of imaging possibility. We therefore were studying the use of stable rubidium (Rb) for labeling having the advantage that the in vitro methodology can be controlled by the addition of 86Rb. Human platelets derived from healthy volunteers as well as patients suffering from clinically manifested atherosclerosis and / or hyperlipidaemia were examined after anticoagulation with acid citrate dextrose. Platelets (>1.109) were isolated using a protocol defined by us earlier using Monovette vials for easy and safe handling under closed conditions. After isolation platelets were incubated in a volume of 1 ml freshly prepared Tyrode buffer (pH 6,2) with 5 mg rubidium at various temperatures (40C, 220C, 370C) using a variety of different incubation times (10, 20, 30 and 60 minutes, respectively) and differing cellular density (1.106 - 1.109 /ml. Labeling efficiency was assessed by means of radioactive counting as well as by coupled plasma sector field mass spectrometry (ICPSFMS). Labeling efficiencies ranged at about 10 % and in contrast to 111In-oxine was not temperature-dependent. Considering the detection limit of ICP-SFMS and labeling efficiency 0,5 - 1 mg Rb are finally injected into the patient allowing in-vivo monitoring of kinetics. These findings indicate that ICP-SFMS monitoring Rb labeled blood cells is feasible and may even replace radiolabeling in those patients where subsequent gamma-camera imaging is not required. (author)

  12. Role of bio-effect models in improving radiotherapy of cancer

    Application of linear quadratic model of cell survival in radiotherapy has enabled to successfully predict the response of both the normal tissues and tumours. Even the simplest form of BED (biological effective dose) equation for fractionated radiotherapy could precisely predict the late normal tissue complications resulting from large dose per fraction. These observations have led to the development MFD (multiple fractions daily) protocol, with the specific objective of reducing late normal tissue morbidity. Protraction of treatment and consequent loss of BED and tumour control; multiple fractions delivered without adequate intervals resulting in incomplete repair of sub-lethal damage and consequent normal tissue complications, have been explained successfully by the LQ model. In the recent past LDR (low dose rate) brachytherapy is mostly replaced by HDR (high dose rate) technique. A series of calculations based on tumour bio-kinetics parameters, as well as the geometric sparing provides a sound rationale for replacing LDR technique by HDR technique. Some of the calculations relevant to this will be presented during this talk. Bio-effect models can also provide insight in to the rationale of RIT (radio-immunotherapy). With an adequate knowledge of biological half-life of antibodies in the tumour/critical organs, and biological uptake half-time in the tumour, it is possible to evaluate the efficacy of a number of radio-nuclides in RIT. Calculations based on LQ models suggest that longer lived isotopes such as 32P, 86Rb, 144mIn may have an advantage over the shorter lived radio-nuclides. A clear knowledge of the various parameters like/values, potentially doubling time of tumour and other bio-kinetic parameters may hold the key for successful application of bio-effect models in predicting the response to radiotherapy. Feedback from the clinics will further help in refining and validating the existing models. (author)

  13. Influence of fentanyl and morphine on intestinal circulation

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-06-01

    The influence of fentanyl and morphine on the intestinal circulation was evaluated in an isolated loop preparation in 37 dogs anesthetized with pentobarbital intravenously. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mm Hg. A mixture of /sup 86/Rb and 9-micron spheres labeled with /sup 141/Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A strong correlation was found between the clearances of rubidium and microspheres (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-micron spheres through the intestines reflects the shunting of blood through nonnutritive vessels. Intravenous fentanyl decreased oxygen uptake (O/sub 2/up), and vascular resistance (VR), and increased blood flow (BF), rubidium and microsphere clearances (Cl-Rb, Cl-Sph, respectively), and permeability--surface area product (PS) in a dose-related fashion. Intravenous morphine in a dose of 1 mg X kg-1 increased Cl-Rb (nutritive BF) without changes in total (nutritive and nonnutritive) BF. This increase in nutritive BF is probably related to morphine-induced histamine release. Morphine in a dose of 5 mg X kg-1 was accompanied by vasoconstriction that was completely abolished by alpha-adrenoceptor blockade. The data suggest that morphine-induced intestinal vasoconstriction is mediated via a release of epinephrine, apparently from the adrenal medulla. It is concluded that changes in the intestinal circulation during anesthesia with narcotics might play a certain role in the cardiovascular homeostasis during anesthesia and surgery. An increase in oxygen content in portal venous blood, resulting from a decrease in intestinal oxygen uptake, should facilitate hepatic oxygenation.

  14. Influence of fentanyl and morphine on intestinal circulation

    The influence of fentanyl and morphine on the intestinal circulation was evaluated in an isolated loop preparation in 37 dogs anesthetized with pentobarbital intravenously. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mm Hg. A mixture of 86Rb and 9-micron spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A strong correlation was found between the clearances of rubidium and microspheres (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-micron spheres through the intestines reflects the shunting of blood through nonnutritive vessels. Intravenous fentanyl decreased oxygen uptake (O2up), and vascular resistance (VR), and increased blood flow (BF), rubidium and microsphere clearances (Cl-Rb, Cl-Sph, respectively), and permeability--surface area product (PS) in a dose-related fashion. Intravenous morphine in a dose of 1 mg X kg-1 increased Cl-Rb (nutritive BF) without changes in total (nutritive and nonnutritive) BF. This increase in nutritive BF is probably related to morphine-induced histamine release. Morphine in a dose of 5 mg X kg-1 was accompanied by vasoconstriction that was completely abolished by alpha-adrenoceptor blockade. The data suggest that morphine-induced intestinal vasoconstriction is mediated via a release of epinephrine, apparently from the adrenal medulla. It is concluded that changes in the intestinal circulation during anesthesia with narcotics might play a certain role in the cardiovascular homeostasis during anesthesia and surgery. An increase in oxygen content in portal venous blood, resulting from a decrease in intestinal oxygen uptake, should facilitate hepatic oxygenation

  15. Altered sensitivity of system A amino acid transport to ouabain in normal and transformed C3H-10T1/2 cells during the cell cycle

    Quiescent C3H-10T1/2 mouse fibroblasts that have not undergone any type of stress have a relatively low rate of 2-aminoisobutyrate (Aib) uptake by means of system A, which is primarily energized by the transmembrane Na+ chemical gradient potential. System A activity in these cells is not sensitive to ouabain or proton ionophores. In contrast, methylcholanthrene-transformed and cofluent C3H-10T1/2 cells treated with ouabain utilize the membrane potential generated by the Na+, K+-ATPase pump to drive Aib transport by means of system A as shown by the sensitivity of transport activity to ouabain and proton ionophores. Since glucose is present during the assay, the proton ionophores do not affect the availability of ATP, as indicated by the undiminished uptake of 86Rb+ by the Na+, K+-ATPase pump. As cells progress through the G1 phase of the cell cycle, they show an increased system A activity prior to entry into the S phase, which is also dependent on the electrogenicity of the Na+, K+-ATPase pump. There appears to be in all these cases a qualitative shift in the bioenergetic mechanism for the uptake of Aib as well as a marked quantitative increase in Aib uptake. The high activity after ouabain treatment was sustained in the transformed cells after removal of the ouabain, whereas in the confluent 10T1/2 cells the rate of uptake decayed rapidly, suggesting a difference in the mode of regulation. The authors conclude that transformed cells and normal cells in late G1 or under stress make use of the membrane potential generated by the Na+, K+-ATPase pump to drive amino acid uptake by means of system A

  16. Cyclosporine suppression of lymphocyte recruitment, regional blood flow, and vascular permeability at sites of allogeneic cellular interactions

    Although cyclosporine (CsA) has been thought to act primarily on the afferent phase of the immune response, we can demonstrate that it also acts at the efferent phase. The effect of CsA on lymphocyte recruitment (LR), regional blood flow (RBF), and vascular permeability (VP) was studied in paired, healed, subcutaneously placed urethane sponge grafts inoculated with specifically sensitized lymphocytes (SSLs) and allogeneic target cells. Intravenous injection of 111In-labelled unsensitized lymphocytes, 86RbCl and 125I-labelled albumin were used to assess LR, RBF, and VP, respectively. Suspensions of SSL and targets in CsA at 10 and 1 microgram/ml prior to graft inoculation markedly reduce the preferential increase in LR to the site of interaction between SSLs and targets bearing the sensitizing alloantigen (P less than 0.002 for both). Similarly, CsA blocks the preferential increase in RBF (P . 0.017) and VP (P less than 0.002) to the graft site. These effects persist for at least 24 hours. If SSLs and targets are washed after incubation with CsA, LR is still reduced. These results are consistent with the idea that cell-bound CsA blocks the elaboration of lymphokines which results from the interaction between SSLs and specific alloantigen in vivo. These lymphokines increase RBF and VP and are accompanied by an increase in LR. Inhibition of these vascular effects may prevent the recruitment of additional lymphocytes to the graft site. CsA may, therefore, prevent or interrupt allograft rejection by blocking amplification of the rejection mechanism at the graft site

  17. Mechanisms of mercurial and arsenical inhibition of tyrosine absorption in intestine of the winter flounder Pseudopleuronectus americanus

    Musch, M.W.; Chauncey, B.; Schmid, E.C.; Kinne, R.K.; Goldstein, L. (Mount Desert Island Biological Laboratory, Salsbury Cove, ME (USA))

    1990-06-01

    Effects of HgCl2 (100 microM) para-chloromercuribenzene sulfonate (PCMBS) (1 mM), and oxophenylarsine (OPA) (250 microM) were determined on (a) the rate of Na pump activity in intact winter flounder intestine; (b) activity of Na-K-ATPase in tissue homogenates; and (c) Na-dependent and Na-independent uptake of tyrosine in brush border membrane vesicles. Initial rate of uptake (influx) of 86Rb from the serosal solution of tissues mounted in Ussing chambers, a measure of Na-K-ATPase activity in the intact cell, was inhibited by all three agents with differing time courses. Rapidly permeating HgCl2 inhibited influx to the same degree as ouabain at 30 min, whereas the effects of PCMBS and OPA required 90 min. Cell potassium was also measured as an indirect indicator of ATPase activity and cell membrane permeability. All three agents decreased cell K, although effects on cell K lagged behind those for inhibition of the ATPase. At the concentrations used in the Ussing chamber (or at one-tenth concentration), all agents completely inhibited Na-K-ATPase activity in enzyme assays performed with tissue homogenates. In contrast, only HgCl2 decreased Na-dependent uptake of tyrosine by brush border membrane vesicles. These results suggest that mercurial and arsenical effects on tyrosine absorption are due to inhibition of the Na-K-ATPase thus decreasing the driving force for the cellular uptake by the Na-tyrosine cotransport system. Direct effects on Na-tyrosine cotransport may play a role in the inhibition observed with HgCl2, but not for PCMBS or OPA.

  18. Tectonic-and petrological interpretation of geochronological data on the basement at the Southeast border of the Quadrilatero Ferrifero, Minas Gerais, Brazil

    In an attempt to elucidate the regional geological evolution of the Ouro Preto and Mariana Districts, SE Quadrilatero Ferrifero, Minas Gerais, the available petrographical and structural data were interpreted together with 5 Rb/Sr and 7 K/Ar age determinations. Various types of metamorphic rocks were identified, and four phases of regional petrographic evolution could be distinguished: a) pre-metamorphic phase indicated by relict sedimentary and other textures; b) pre-deformation metamorphic phase, manifested by several minerals, such as microcline; c) major syntectonic crystallization phase associated with the main regional diastrophism, presumaby the Minas orogeny; d) post-deformation phase, with retrograde metamorphic minerals. With one exception, the apparent K/Ar ages obtained on biotites and amphiboles were concordant, ranging between 480 and 540 m.y., and can be referred to the terminal episodes of cooling in the Brazilian cycle. The Rb/Sr data obtained from 3 whole-rock analyses, when plotted on a Sr87/Sr86 - Rb87/Sr86 diagram, indicated an age of approximately 2.000m.y., with an initial Sr87/Sr86 ratio of 0.711. In this diagram, 2 other speciments from a single outerop plotted significantly above of the reference isochron of 2.000m.y. The apparent ages of about 2.700 m.y. are concordant with those for the Barbacena Group which occurs more toward the eastern side of the study area. From interpretation of petrographical and structural data, the following regional geological evolution can be inferred; a)2.700m.y. - Formation of rocks during the pre-Minas episode (diastrophism in Barbacena Series, or in the Bacao Complex; b) 2.000m.y. - Trans-Amazonian cycle - Main phase of syntectonic crystallization - Minas Series diastrophism; c) 500-600m.y. - Brazilian cycle - retrograde metamorphism, thrust tectonics and regional fracturing. (Author)

  19. Vasopressin alters the mechanism of apical Cl- entry from Na+:Cl- to Na+:K+:2Cl- cotransport in mouse medullary thick ascending limb

    Experiments were performed using in vitro perfused medullary thick ascending limbs of Henle (MTAL) and in suspensions of MTAL tubules isolated from mouse kidney to evaluate the effects of arginine vasopressin (AVP) on the K+ dependence of the apical, furosemide-sensitive Na+:Cl- cotransporter and on transport-related oxygen consumption (QO2). In isolated perfused MTAL segments, the rate of cell swelling induced by removing K+ from, and adding one mM ouabain to, the basolateral solution [ouabain(zero-K+)] provided an index to apical cotransporter activity and was used to evaluate the ionic requirements of the apical cotransporter in the presence and absence of AVP. In the absence of AVP cotransporter activity required Na+ and Cl-, but not K+, while the presence of AVP the apical cotransporter required all three ions. 86Rb+ uptake into MTAL tubules in suspension was significant only after exposure of tubules to AVP. Moreover, 22Na+ uptake was unaffected by extracellular K+ in the absence of AVP while after AVP exposure 22Na+ uptake was strictly K+-dependent. The AVP-induced coupling of K+ to the Na+:Cl- cotransporter resulted in a doubling in the rate of NaCl absorption without a parallel increase in the rate of cellular 22Na+ uptake or transport-related oxygen consumption. These results indicate that arginine vasopressin alters the mode of a loop diuretic-sensitive transporter from Na+:Cl- cotransport to Na+:K+:2Cl- cotransport in the mouse MTAL with the latter providing a distinct metabolic advantage for sodium transport. A model for AVP action on NaCl absorption by the MTAL is presented and the physiological significance of the coupling of K+ to the apical Na+:Cl- cotransporter in the MTAL and of the enhanced metabolic efficiency are discussed

  20. Ischemia-induced stimulation of Na-K-Cl cotransport in cerebral microvascular endothelial cells involves AMP kinase.

    Wallace, Breanna K; Foroutan, Shahin; O'Donnell, Martha E

    2011-08-01

    Increased blood-brain barrier (BBB) Na-K-Cl cotransporter activity appears to contribute to cerebral edema formation during ischemic stroke. We have shown previously that inhibition of BBB Na-K-Cl cotransporter activity reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of ischemic stroke. We have also shown that the BBB cotransporter is stimulated by the ischemic factors hypoxia, aglycemia, and arginine vasopressin (AVP), although the mechanisms responsible are not well understood. AMP-activated protein kinase (AMPK), a key mediator of cell responses to stress, can be activated by a variety of stresses, including ischemia, hypoxia, and aglycemia. Previous studies have shown that the AMPK inhibitor Compound C significantly reduces infarct in mouse MCAO. The present study was conducted to evaluate the possibility that AMPK participates in ischemic factor-induced stimulation of the BBB Na-K-Cl cotransporter. Cerebral microvascular endothelial cells (CMEC) were assessed for Na-K-Cl cotransporter activity as bumetanide-sensitive (86)Rb influx. AMPK activity was assessed by Western blot analysis and immunofluorescence methods using antibodies that detect total versus phosphorylated (activated) AMPK. We found that hypoxia (7% and 2% O(2)), aglycemia, AVP, and oxygen-glucose deprivation (5- to 120-min exposures) increase activation of AMPK. We also found that Compound C inhibition of AMPK reduces hypoxia-, aglycemia-, and AVP-induced stimulation of CMEC Na-K-Cl cotransporter activity. Confocal immunofluorescence of perfusion-fixed rat brain slices revealed the presence of AMPK, both total and phosphorylated kinase, in BBB in situ of both control and ischemic brain. These findings suggest that ischemic factor stimulation of the BBB Na-K-Cl cotransporter involves activation of AMPK. PMID:21562306

  1. Use of an external source (60Co) for 32P detection efficiency determination by the Cerenkov effect, in soil extracts

    The detection of 32P in aqueous extracts is usually made with the aid of a Geiger-Muller detector, with thin window and sample on a planchet. Presently the technique is being developed of detection of high energy beta particles emitters (32P, 42K, 86Rb) through the Cerenkov effect, using a commercial liquid scintillation system. This technique, despite being approximately 30 times more sensitive, has the inconvenience of varying the detection efficiency, mainly for color samples (soil extracts, for instance). From this stems the need for determining the detection efficiency for each sample. The internal standardization and channels ratio methods show a series of drawbacks, mainly the non-reutilization of the samples (1st method) and statistical uncertainty for low activity samples (2nd method). The elimination of these dreawbacks can be achieved through the utilization of the external standardization method. A 60Co source with 1,4 μCi activity has been adapted to the sample elevator of the detector system, and a comparison was made with the channels ratio method to evaluate the efficiency of 32P detection in soil extracts (P extraction and fractionation). The external standardization method showed to be more accurate, besides being influenced to a lesser degree by high voltage variation, sample volume and vial types. In the case of large samples, it is advisable to carry out detection in vials filled up to their full capacity; in the case of small samples, the whole volume should be transferred to the vials and completed up to 9 ml for nylon vials,10 ml for glass vials and 11 to 14 ml for polyethilene vials. On the other hand, plastic vials showed higher detection efficiency than ones. As to background radiation, the lowest rates were given by nylon vials and the highest by Beckman glass vials

  2. Receptor-mediated inhibition of adenylate cyclase and stimulation of arachidonic acid release in 3T3 fibroblasts. Selective susceptibility to islet-activating protein, pertussis toxin

    Thrombin exhibited diverse effects on mouse 3T3 fibroblasts. It (a) decreased cAMP in the cell suspension, (b) inhibited adenylate cyclase in the Lubrol-permeabilized cell suspension in a GTP-dependent manner, increased releases of (c) arachidonic acid and (d) inositol from the cell monolayer prelabeled with these labeled compounds, (e) increased 45Ca2+ uptake into the cell monolayer, and (f) increased 86Rb+ uptake into the cell monolayer in a ouabain-sensitive manner. Most of the effects were reproduced by bradykinin, platelet-activating factor, and angiotensin II. The receptors for these agonists are thus likely to be linked to three separate effector systems: the adenylate cyclase inhibition, the phosphoinositide breakdown leading to Ca2+ mobilization and phospholipase A2 activation, and the Na,K-ATPase activation. Among the effects of these agonists, (a), (b), (c), and (e) were abolished, but (d) and (f) were not, by prior treatment of the cells with islet-activating protein (IAP), pertussis toxin, which ADP-ribosylates the Mr = 41,000 protein, the alpha-subunit of the inhibitory guanine nucleotide regulatory protein (Ni), thereby abolishing receptor-mediated inhibition of adenylate cyclase. The effects (a), (c), (d), and (e) of thrombin, but not (b), were mimicked by A23187, a calcium ionophore. The effects of A23187, in contrast to those of receptor agonists, were not affected by the treatment of cells with IAP. Thus, the IAP substrate, the alpha-subunit of Ni, or the protein alike, may play an additional role in signal transduction arising from the Ca2+-mobilizing receptors, probably mediating process(es) distal to phosphoinositide breakdown and proximal to Ca2+ gating

  3. Early metabolic effects and mechanism of ammonium transport in yeast

    Studies were performed to define the effects and mechanism of NH+4 transport in yeast. The following results were obtained. Glucose was a better facilitator than ethanol-H2O2 for ammonium transport; low concentrations of uncouplers or respiratory inhibitors could inhibit the transport with ethanol as the substrate. With glucose, respiratory inhibitors showed only small inhibitory effects, and only high concentrations of azide or trifluoromethoxy carbonylcyanide phenylhydrazone could inhibit ammonium transport. Ammonium in the free state could be concentrated approximately 200-fold by the cells. Also, the addition of ammonium produced stimulation of both respiration and fermentation; an increased rate of H+ extrusion and an alkalinization of the interior of the cell; a decrease of the membrane potential, as monitored by fluorescent cyanine; an immediate decrease of the levels of ATP and an increase of ADP, which may account for the stimulation of both fermentation and respiration; and an increase of the levels of inorganic phosphate. Ammonium was found to inhibit 86Rb+ transport much less than K+. Also, while K+ produced a competitive type of inhibition, that produced by NH4+ was of the noncompetitive type. From the distribution ratio of ammonium and the pH gradient, an electrochemical potential gradient of around -180 mV was calculated. The results indicate that ammonium is transported in yeast by a mechanism similar to that of monovalent alkaline cations, driven by a membrane potential. The immediate metabolic effects of this cation seem to be due to an increased [H+]ATPase, to which its transport is coupled. However, the carriers seem to be different. The transport system studied in this work was that of low affinity

  4. Physiological and biochemical studies of newly synthesized muscarinic acetylcholine receptors in embryonic chicken heart

    Exposure of either chicken embryos in ovo or cultured embryonic chicken cardiac cells in vitro to the muscarinic agonist carbachol results in a 70-90% decrease in the number of muscarinic acetylcholine receptors (mAChR) expressed in cardiac cells. Block of agonist-receptor interactions in ovo with the antagonist atropine or removal of the agonist in vitro results in a gradual increase in mAChR number, reaching the control level in 14 hr. Measurements of physiological sensitivity of atria or cultured cells show that, even after the complete recovery of receptor number, the sensitivity to agonist is reduced. The sensitivity of the mAChR-mediated inhibition of adenylate cyclase is also decreased at this time. Newly synthesized mAChR which appear following affinity alkylation in cultured cells are also poorly coupled to the stimulation of 86Rb+ efflux, indicating that decreased physiological sensitivity is not due to an unknown effect of long-term agonist exposure on general cellular function, but rather reflects an intrinsic property of newly synthesized mAChR. This increase in sensitivity is also not blocked by cycloheximide. The increase in sensitivity of the mAChR-mediated responses is due neither to a lack of expression of newly synthesized mAChR on the surface nor to reduced agonist affinity of the mAChR. The diminished sensitivity and subsequent maturation observed in cells containing newly synthesized receptors is due either to a small change in mAChR, or to a change in an as-yet-undefined component of the mAChR transduction system; this alteration represents a novel locus for modulation of cholinergic signals in the heart

  5. Differential mechanisms of Cantú syndrome-associated gain of function mutations in the ABCC9 (SUR2) subunit of the KATP channel.

    Cooper, Paige E; Sala-Rabanal, Monica; Lee, Sun Joo; Nichols, Colin G

    2015-12-01

    Cantú syndrome (CS) is a rare disease characterized by congenital hypertrichosis, distinct facial features, osteochondrodysplasia, and cardiac defects. Recent genetic analysis has revealed that the majority of CS patients carry a missense mutation in ABCC9, which codes for the sulfonylurea receptor SUR2. SUR2 subunits couple with Kir6.x, inwardly rectifying potassium pore-forming subunits, to form adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels, which link cell metabolism to membrane excitability in a variety of tissues including vascular smooth muscle, skeletal muscle, and the heart. The functional consequences of multiple uncharacterized CS mutations remain unclear. Here, we have focused on determining the functional consequences of three documented human CS-associated ABCC9 mutations: human P432L, A478V, and C1043Y. The mutations were engineered in the equivalent position in rat SUR2A (P429L, A475V, and C1039Y), and each was coexpressed with mouse Kir6.2. Using macroscopic rubidium ((86)Rb(+)) efflux assays, we show that K(ATP) channels formed with P429L, A475V, or C1039Y mutants enhance K(ATP) activity compared with wild-type (WT) channels. We used inside-out patch-clamp electrophysiology to measure channel sensitivity to ATP inhibition and to MgADP activation. For P429L and A475V mutants, sensitivity to ATP inhibition was comparable to WT channels, but activation by MgADP was significantly greater. C1039Y-dependent channels were significantly less sensitive to inhibition by ATP or by glibenclamide, but MgADP activation was comparable to WT. The results indicate that these three CS mutations all lead to overactive K(ATP) channels, but at least two mechanisms underlie the observed gain of function: decreased ATP inhibition and enhanced MgADP activation. PMID:26621776

  6. Properties of the Ca-activated K+ channel in pancreatic beta-cells.

    Atwater, I; Rosario, L; Rojas, E

    1983-12-01

    The existence of [Ca2+]i-activated K+-channels in the pancreatic beta-cell membrane is based in two observations: quinine inhibits K+-permeability and, increasing intracellular Ca2+ stimulates it. The changes in K+-permeability of the beta-cell have been monitored electrically by combining measurements of the dependence of the membrane potential on external K+ concentration and input resistance. The changes in the passive 42K and 86Rb efflux from the whole islet have been measured directly. Intracellular Ca2+ has been increased by various means, including increasing extracellular Ca2+, addition of the Ca2+-ionophore A23187 or noradrenaline and application of mitochondrial uncouplers and blockers. In addition to quinine, many other substances have been found to inhibit or modulate the [Ca2+]i-activated K+-channel. The most important of these is the natural stimulus for insulin secretion, glucose. Glucose may inhibit K+-permeability by lowering intracellular Ca2+. Glibenclamide, a hypoglycaemic sulphonylurea, is about 25 times more active than quinine in blocking the K+-channel in beta-cells. The methylxanthines, c-AMP, various calmodulin inhibitors and Ba2+ also inhibit K+-permeability. Genetically diabetic mice have been studied and show an alteration in the [Ca2+]i-activated K+-channel. It is concluded that the [Ca2+]i-activated K+-channel plays a major role in the normal function of the pancreatic beta-cell. The study of its properties should prove valuable for the understanding and treatment of diabetes. PMID:6323007

  7. Effects of atrial and brain natriuretic peptides upon cyclic GMP levels, potassium transport, and receptor binding in rat astrocytes

    The ability of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) to alter cyclic GMP levels and NaKCl cotransport in rat neocortical astrocytes was determined. At concentrations of 10(-9)-10(-6) M, rat ANP99-126 (rANF), rat ANP102-126 (auriculin B), and rat ANP103-126 (atriopeptin III) stimulated 6- to 100-fold increases in cyclic GMP levels. Porcine BNP (pBNP) and rat BNP (rBNP) were 20%-90% as effective as rANF over most of this concentration range, although 10(-6) M pBNP produced a greater effect than rANF. NaKCl cotransport as measured by bumetanide-sensitive 86Rb+ influx was not altered by exposure of astrocytes to 10(-6)M rANF, pBNP, or rBNP. Both pBNP and rBNP, as well as rat ANP103-123 (atriopeptin I) and des[gl18, ser19, gly20, leu21, gly22] ANF4-23-NH2 (C-ANF4-23) strongly competed for specific 125I-rANF binding sites in astrocyte membranes with affinities ranging from 0.03 to 0.4 nM, suggesting that virtually all binding sites measured at subnanomolar concentrations of 125I-rANF were of the ANP-C (ANF-R2) receptor subtype. These receptors are thought to serve a clearance function and may be linked to a guanylate cyclase activity that is chemically and pharmacologically distinct from that coupled to ANP-A (ANF-R1) receptors. ANP receptors on astrocytes may function in limiting the access of ANP and BNP to neurons involved in body fluid and cardiovascular regulation

  8. Tumor necrosis factor-alpha induces Cl- and K+ secretion in human distal colon driven by prostaglandin E2.

    Schmitz, H; Fromm, M; Bode, H; Scholz, P; Riecken, E O; Schulzke, J D

    1996-10-01

    Increased levels of tumor necrosis factor-alpha (TNF-alpha) have been found in, for example, inflammatory bowel disease (IBD) and human immunodeficiency virus (HIV) infection. To investigate a possible contribution of TNF-alpha to the pathogenesis of diarrhea in these diseases, ion transport of human distal colon was studied in the Ussing chamber in vitro. Serosal addition of TNF-alpha increased short-circuit current (Isc) of partially stripped tissues in a dose-dependent manner. Maximum Isc increase of 1.8 +/- 0.2 mumol.h-1.cm-2 was reached after 60 +/- 9 min at 200 ng/ml TNF-alpha. Bidirectional tracer flux measurements revealed that TNF-alpha induced an increase in 36 Cl serosal-to-mucosal flux, a decrease in 36Cl- mucosal-to-serosal flux, and a slight increase in K+ secretion indicated by an increased secretory 86Rb net flux. In the highly differentiated colonic epithelial cell line HT-29/B6, TNF-alpha had no effect on Isc, suggesting a mediation step located in the subepithelium. This supposition was supported by measurements on totally stripped human tissues, since removal of subepithelial layers by total stripping reduced the TNF-alpha effect by 40%. Experiments with tetrodotoxin (10(-6)M) indicated that the TNF-alpha effect was not mediated by the enteric nervous system. The specific 5-lipoxygenase blocker ICI-230487 (5 x 10(-8)M) also had no effect on TNF-alpha action. In contrast, inhibition of cyclooxygenase by indomethacin (10(-6)M inhibited the effect of TNF-alpha. Radioimmunoassay of prostaglandin E2 (PGE2) in the serosal bathing solution revealed an increase in PGE2 production/release after addition of TNF-alpha, which paralleled the Isc response. We conclude that TNF-alpha changed Cl- and K+ transport toward secretion in human colon. This effect was mediated by PGE2 produced by subepithelial cells. Thus TNF-alpha could be a mediator of diarrhea during intestinal inflammation, e.g., in IBD and HIV infection. PMID:8897887

  9. Vasopressin alters the mechanism of apical Cl- entry from Na+:Cl- to Na+:K+:2Cl- cotransport in mouse medullary thick ascending limb

    Sun, A.; Grossman, E.B.; Lombardi, M.; Hebert, S.C. (Brigham and Women' s Hospital, Boston, MA (USA))

    1991-02-01

    Experiments were performed using in vitro perfused medullary thick ascending limbs of Henle (MTAL) and in suspensions of MTAL tubules isolated from mouse kidney to evaluate the effects of arginine vasopressin (AVP) on the K+ dependence of the apical, furosemide-sensitive Na{sup +}:Cl{sup {minus}} cotransporter and on transport-related oxygen consumption (QO{sub 2}). In isolated perfused MTAL segments, the rate of cell swelling induced by removing K+ from, and adding one mM ouabain to, the basolateral solution (ouabain(zero-K+)) provided an index to apical cotransporter activity and was used to evaluate the ionic requirements of the apical cotransporter in the presence and absence of AVP. In the absence of AVP cotransporter activity required Na{sup +} and Cl{sup {minus}}, but not K{sup +}, while the presence of AVP the apical cotransporter required all three ions. {sup 86}Rb{sup +} uptake into MTAL tubules in suspension was significant only after exposure of tubules to AVP. Moreover, {sup 22}Na{sup +} uptake was unaffected by extracellular K+ in the absence of AVP while after AVP exposure {sup 22}Na{sup +} uptake was strictly K{sup +}-dependent. The AVP-induced coupling of K{sup +} to the Na{sup +}:Cl{sup {minus}} cotransporter resulted in a doubling in the rate of NaCl absorption without a parallel increase in the rate of cellular {sup 22}Na{sup +} uptake or transport-related oxygen consumption. These results indicate that arginine vasopressin alters the mode of a loop diuretic-sensitive transporter from Na{sup +}:Cl{sup {minus}} cotransport to Na{sup +}:K{sup +}:2Cl{sup {minus}} cotransport in the mouse MTAL with the latter providing a distinct metabolic advantage for sodium transport. A model for AVP action on NaCl absorption by the MTAL is presented and the physiological significance of the coupling of K{sup +} to the apical Na{sup +}:Cl{sup {minus}} cotransporter in the MTAL and of the enhanced metabolic efficiency are discussed.

  10. Nutrient effects of different amount of potassium applied on flue-cured tobacco plant

    The nutrient effects of different amount of potassium fertilizer on flue-cured tobacco plant were studied by using 86Rb. The results showed that at the topping stage of flue-cured tobacco plant, with increasing amount of applied potassium, the amount of K2O in the leaves of flue-cured tobacco plant in the treatment of applying 2.5 g K2O/plant was 18.57%, 17.43% and 3.29% higher than those of control, the treatments of applying 1.5g and 2.0g K2O respectively. The amount of K2O absorbed from KNO3 by single flue-cured tobacco plant in the treatment of applying 3.0g K2O/plant was 19.74%, 13.57%, 13.01% higher than those of the treatments of applying 1.5g, 2.0g and 2.5g K2O/plant respectively. The total amount of K2O absorbed by a single flue-cured tobacco plant in the treatment of 2.5g K2O/plant was 20.70%, 8.93%, 8.16% higher than those of control, the treatment of 1.5g and 2.0g K2O/plant, respectively. At the budding stage of flue-cured tobacco plant, with increasing of the amount of applied K2O, the amount of K2O absorbed from soil by a single flue-cured tobacco plant in the treatments of 2.0g, 2.5g, 3.0g K2O/plant were 5.95%, 11.45%, 15.97% lower than that of the treatment of 1.5g K2O/plant. The utilization rate of K2O in the treatments of 2.0 g, 2.5 g, 3.0 g K2O/plant were 10.89%, 28.90%, 42.50% lower than that of the treatment of 1.5g K2O/plant. At the topping stage, the dry weight of a flue-cured tobacco plant with treatment of 2.5g K2O/plant was higher than those of control, the treatments of 1.5 g, 2.0 g K2O/plant, respectively

  11. The ATPase activity of saponin-treated rat erythrocytes: regulation by monovalent cations, calcium, ouabain, and furosemide.

    Petrunyaka, V V; Panyushkina, E A; Severina, E P; Orlov, S N

    1990-12-14

    The ATPase activities were studied in rat erythrocytes permeabilized with saponin. The concentrations of calcium and magnesium ions were varied within the range of 0.1-60 microM and 50-370 microM, respectively, by using EGTA-citrate buffer. The maximal activity of Ca2(+)-ATPase of permeabilized erythrocytes was by one order of magnitude higher, whereas the Ca2(+)-binding affinity was 1.5-2 times higher than that in erythrocyte ghosts washed an isotonic solution containing EGTA. Addition of the hemolysate restored the kinetic parameters of ghost Ca2(+)-ATPase practically completely, whereas in the presence of exogenous calmodulin only part of Ca2(+)-ATPase activity was recovered. Neither calmodulin nor R24571, a highly potent specific inhibitor of calmodulin-dependent reactions, influenced the Ca2(+)-ATPase activity of permeabilized erythrocytes. At Ca2+ concentrations below 0.7 microM, ouabain (0.5-1 mM) activated whereas at higher Ca2+ concentrations it inhibited the Ca2(+)-ATPase activity. Taking this observation into account the Na+/K(+)-ATPase was determined as the difference of between the ATPase activities in the presence of Na+ and K+ and in the presence of K+ alone. At physiological concentration of Mg2+ (370 microM), the addition of 0.3-1 microM Ca2+ increased Na+/K(+)-ATPase activity by 1.5-3-fold. Higher concentrations of this cation inhibited the enzyme. At low Mg2+ concentration (e.g., 50 microM) only Na+/K(+)-ATPase inhibition by Ca2+ was seen. It was found that at [NaCl] less than 20 mM furosemide was increased ouabain-inhibited component of ATPase in Ca2(+)-free media. This activating effect of furosemide was enhanced with a diminution of [Na+] upto 2 mM and did not reach the saturation level unless the 2 mM of drug was used. The activating effect of furosemide on Na+/K(+)-ATPase activity confirmed by experiments in which the ouabain-inhibited component was measured by the 86Rb+ influx into intact erythrocytes. PMID:2175654

  12. Structure-function relationships in the Na,K-ATPase α subunit: site-directed mutagenesis of glutamine-111 to arginine and asparagine-122 to aspartic acid generates a ouabain-resistant enzyme

    Na,K-ATPases from various species differ greatly in their sensitivity to cardiac glycosides such as ouabain. The sheep and human enzymes are a thousand times more sensitive than the corresponding ones from rat and mouse. To define the region of the α1 subunit responsible for this differential sensitivity, chimeric cDNAs of sheep and rat were constructed and expressed in ouabain-sensitive HeLa cells. The construct containing the amino-terminal half of the rat α1 subunit coding region and carboxyl-terminal half of the sheep conferred the ouabain-resistant phenotype to HeLa cells while the reverse construct did not. This indicates that the determinants involved in ouabain sensitivity are located in the amino-terminal half of the Na,K-ATPase α subunit. By use of site-directed mutagenesis, the amino acid sequence of the first extracellular domain (H1-H2) of the sheep α1 subunit was changed to that of the rat. When expressed in HeLa cells, this mutated sheep α1 construct, like the rat/sheep chimera, was able to confer ouabain resistance to these cells. Furthermore, similar results were observed when HeLa cells were transfected with a sheep α1 cDNA containing only two amino acid substitutions. The resistant cells, whether transfected with the rat α1 cDNA, the rat/sheep chimera, or the mutant sheep α1 cDNAs, exhibited identical biochemical characteristics including ouabain-inhibitable cell growth, 86Rb+ uptake, and Na,K-ATPase activity. These results demonstrate that the presence of arginine and aspartic acid on the amino end and carboxyl end, respectively, of the H1-H2 extracellular domain of the Na,K-ATPase α subunit together is responsible for the ouabain-resistant character of the rat enzyme and the corresponding residues in the sheep α1 subunit (glutamine and asparagine) are somehow involved in ouabain binding

  13. Hypotonicity and cell volume regulation in shark rectal gland: role of organic osmolytes and F-actin.

    Ziyadeh, F N; Mills, J W; Kleinzeller, A

    1992-03-01

    Hypotonic stress (reduction of external tonicity from approximately 900 mosM and 295 mM NaCl to approximately 600 mosM and 135 mM NaCl) produced a relatively slow regulatory volume decrease (RVD) in dogfish shark (Squalus acanthias) rectal gland cells. During the 5-h experiment, cell K+ content remained unchanged; cell content of Na+ and Cl- dropped in the initial swelling phase by some 50% (reflecting the corresponding reduction in medium NaCl), and then remained unchanged during volume recovery phase. Also, cellular fluxes of 86Rb+ and urea were not affected by hypotonic stress. However, hypotonicity enhanced 10- to 20-fold the efflux of organic cell osmolytes taurine, betaine, and trimethyloxamine, and this accounted for the loss of osmotically obliged water during RVD. Enhancement of osmolyte efflux by hypotonic stress was abolished by readjusting the low-Na+ saline to isotonicity (approximately 900 mosM) with innocuous cations (choline+, Li+, or N-methylglucamine+). The results suggest that reduction of medium tonicity may be the determinant for the RVD response to hypotonic stress. The above properties of the observed RVD were also displayed when studying changes on cell F-actin at the basolateral cell face; hypotonic stress (medium with 135 mM NaCl) produced a rapid disappearance of fluorescence related to this cytoskeletal component, whereas no such changes were seen in low-Na+ salines made isotonic with choline or N-methylglucamine chloride nor in a saline made hyposmolar by omitting urea. Hence, hypotonicity is required to affect F-actin organization (depolymerization?). These changes of F-actin fluorescence are transient; they were completed within 5-10 min of hypotonic stress, and afterwards a gradual reconstitution of cell F-actin organization was seen. The above observations are consistent with the assumption that, in shark rectal gland cells, transient loss of cytoskeleton (F-actin) organization at the basolateral cell face, induced by hypotonicity

  14. ZZ MCB-JEF2.2, MCB Continuous-Energy Neutron Cross Section Libraries for Temperatures from 300 to 1800 K

    1 - Description of program or function: MCB-JEF2.2 is a continuous-energy cross section libraries in ACE Format suitable for the MCB-1C and MCNP codes. Libraries for various materials were generated at six different Temperatures, and cover the energy range up to 20 MeV. Format: ACE. Number of groups: Continuous energy. Nuclides: H-1, H-2, H-3, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-nat., N-14, N-15, O-16, O-17, Na-23, F-19, Mg-nat., Al-27, Si-nat., P-31, S-32, S-33, S-34, S-36, Cl-nat, K-nat, Ca-nat., Ti-nat, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-59, Ni-60, Ni-61, Ni-62, Ni-64, Cu-nat, Ga-nat, Ge-72, Ge-73, Ge-74, Ge-76, As-75, Se-74, Se-76, Se-77, Se-78, Se-80, Se-82, Br-79, Br-81, Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, Kr-85, Kr-86, Rb-85, Rb-86, Rb-87, Sr-84, Sr-86, Sr-87, Sr-88, Sr-89, Sr-90, Y-89, Y-90, Y-91, Zr-nat, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Nb-94, Nb-95, Mo-nat, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Tc-99, Ru-96, Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, Ru-103, Ru-104, Ru-105, Ru-106, Rh-103, Rh-105, Pd-102, Pd-104, Pd-105, Pd-106, Pd-107, Pd-108, Pd-110, Ag-107, Ag-109, Ag-111, Cd-nat., Cd-106, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-115, Cd-116, In-113, In-115, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-24, Sn-125, Sn-126, Sb-121, Sb-123, Sb-124, Sb-125, Sb-126, Te-120, Te-122, Te-123, Te-124, Te-125, Te-126, Te-127, Te-128, Te-129, Te-130, Te-132, I-127, I-129, I-130, I-131, I-135, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-133, Xe-134, Xe-135, Xe-136, Cs-133, Cs-134, Cs-135, Cs-136, Cs-137, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Ba-140, La-139, La-140, Ce-140, Ce-141, Ce-142, Ce-143, Ce-144, Pr-141, Pr-142, Pr-143, Nd-142, Nd-143, Nd-144, Nd-145, Nd-146, Nd-147, Nd-148, Nd-150, Pm-147, Pm-148, Pm-149, Pm-151, Sm-144, Sm-147, Sm-148, Sm-149, Sm-150, Sm-151, Sm-152, Sm-153, Sm-154, Eu-151, Eu-152, Eu-153, Eu

  15. Aespoe Hard Rock Laboratory. Final report of the first stage of the tracer retention understanding experiments

    The first stage of the Tracer Retention Understanding Experiments (TRUE) was performed as a SKB funded project. The overall objectives of TRUE are to develop the understanding of radionuclide migration and retention in fractured rock, to evaluate the realism in applied model concepts, and to assess whether the necessary input data to the models can be collected from site characterisation. Further, to evaluate the usefulness and feasibility of different model approaches, and finally to provide in situ data on radionuclide migration and retention. The strive for address with multiple approaches is facilitated through a close collaboration with the Aespoe Task Force on Modelling of Groundwater Flow and Transport of Solutes. The TRUE programme is a staged programme which addresses various scales from laboratory (22Na+ 47Ca2+ ≅ 85Sr2+ 86Rb+ ≅ 133Ba2+ The field tracer tests, using essentially the same cocktail of sorbing tracers as in the laboratory, were found to show the same relative sorbtivity as seen in the laboratory. A test using 137Cs showed that after termination of the test, some 63% of the injected activity remained sorbed in the rock. The interpretation of the in situ tests with sorbing tracers was performed using the LaSAR approach, developed as a part of the TRUE project. In this approach the studied flow path is viewed as a part of an open fracture. Key processes are spatially variable advection and mass transfer. The evaluation shows that laboratory diffusion data are not representative for in situ conditions, and that a close fit between field and modelled breakthrough is obtained only when a parameter group which includes diffusion is enhanced with a factor varying between 32-50 for all tracers and experiments (except for Cs) and 137 for Cs. Our interpretation is that the enhancement is mainly due to higher diffusivity/porosity and higher sorption in the part of the altered rim zone of the feature which is accessible over the time scales of the in

  16. ZZ MATXSLIBJ33, JENDL-3.3 based, 175 N-42 photon groups (VITAMIN-J) MATXS library for discrete ordinates multi-group

    1 - Description of program or function: JENDL-3.3 based, 175 neutron-42 photon groups (VITAMIN-J) MATXS library for discrete ordinates multi-group transport codes. Format: MATXS. Number of groups: 175 neutron, 42 gamma-ray. Nuclides: 337 nuclides contained in JENDL-3.3: H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Ge-70, Ge-72, Ge-73, Ge-74, Ge-76, As-75, Se-74, Se-76, Se-77, Se-78, Se-79, Se-80, Se-82, Br-79, Br-81, Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, Kr-85, Kr-86, Rb-85, Rb-87, Sr-86, Sr-87, Sr-88, Sr-89, Sr-90, Y-89, Y-91, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Nb-94, Nb-95, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Tc-99, Ru-96, Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, Ru-103, Ru-104, Ru-106, Rh-103, Rh-105, Pd-102, Pd-104, Pd-105, Pd-106, Pd-107, Pd-108, Pd-110, Ag-107, Ag-109, Ag-110m, Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-116, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-126, Sb-121, Sb-123, Sb-124, Sb-125, Te-120, Te-122, Te-123, Te-124, Te-125, Te-126, Te-127m, Te-128, Te-129m, Te-130, I-127, I-129, I-131, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-133, Xe-134, Xe-135, Xe-136, Cs-133, Cs-134, Cs-135, Cs-136, Cs-137, Ba-130, Ba-132, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Ba-140, La-138, La-139, Ce-140, Ce-141, Ce-142, Ce-144, Pr-141, Pr-143, Nd-142, Nd-143, Nd-144, Nd-145, Nd-146, Nd-147, Nd-148, Nd-150, Pm-147, Pm-148, Pm-148m, Pm-149, Sm-144, Sm-147, Sm-148, Sm-149, Sm-150, Sm-151, Sm-152, Sm-153, Sm-154, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Eu

  17. ZZ-SCALE5.1/COVA-44G, 44-group cross section covariance matrix library extracted from SCALE5.1

    1 - Description: ZZ-SCALE5.1/COVA-44G is a 44-group cross section covariance matrix library retrieved from the SCALE-5.1 package. The package includes the following 4 covariance libraries in COVERX format: - 44GROUPV5COV, Basic ENDF/B-V Covariance Library - 44GROUPV5REC, Recommended ENDF/B-V Covariance Library - 44GROUPV6COV, Basic ENDF/B-VI Covariance Library - 44GROUPV6REC, Recommended ENDF/B-VI Covariance Library The files contain the covariance data for the following reactions or parameters: total, elastic, inelastic, (n,2n), fission, chi, (n,gamma), (n,p), (n,d), (n,t), (n,3He), (n,α), and ν-bar. The nuclides or materials (in ZA order) for which covariance data are provided. In parentheses the total number of the different relative covariance matrices in the four libraries for each nuclide is specified. H-1(10),H-2(3),H-3(2),He-3(2),He-4,Li-6(2),Li-7(3),Be-9(2), B-10(3),B-11(2),C-0(6),N-14(2),N-15,O-16(3),O-17,F-19(3), Na-23(3),Mg-0,Al-27(2),Si-0(3),Si-28,Si-29,Si-29,Si-30, P-31,S-0,S-32,Cl-0,K-0,Ca-0,Sc-45(2),Ti-0, V-0(2),Cr-0(2),Cr-50,Cr-52,Cr-53,Cr-54,Mn-55(3),Fe-0(2), Fe-54,Fe-56,Fe-57,Fe-58,Co-59(3),Ni-0(2),Ni-58,Ni-60, Ni-61,Ni-62,Ni-64,Cu-0,Cu-63,Cu-65,Ga-0,Ge-72, Ge-73,Ge-74,Ge-76,As-75,Se-74,Se-76,Se-77,Se-78, Se-80,Se-82,Br-79,Br-81,Kr-78,Kr-80,Kr-82,Kr-83, Kr-84,Kr-85,Kr-86,Rb-85,Rb-87,Sr-84,Sr-86,Sr-87, Sr-88,Sr-89,Sr-90,Y-89,Y-89,Y-90,Y-91,Zr-0, Zr-90,Zr-91,Zr-92,Zr-93,Zr-94,Zr-96,Nb-93,Nb-93, Nb-94,Nb-95,Mo-0,Mo-94,Mo-95,Mo-96,Mo-97,Tc-99, Ru-96,Ru-99,Ru-100,Ru-101,Ru-102,Ru-104,Ru-105,Ru-106, Rh-103,Rh-105,Pd-102,Pd-104,Pd-105,Pd-106,Pd-107,Pd-108, Pd-110,Ag-107,Ag-109,Ag-111,Cd-0,Cd-106,Cd-108,Cd-110, Cd-111,Cd-112,Cd-113,Cd-114,Cd-116,In-0,In-113,In-115, Sn-112,Sn-114,Sn-115,Sn-116,Sn-117,Sn-118,Sn-119,Sn-120, Sn-122,Sn-124,Sb-121,Sb-123,Sb-124,Te-120,Te-122,Te-123, Te-124,Te-125,Te-126,Te-127(m),Te-128,Te-130,I-127,I-129, I-130,I-131,Xe-124,Xe-126,Xe-128,Xe-129,Xe-130,Xe-131, Xe-132,Xe-133,Xe-134,Xe-135,Xe-136,Cs-133,Cs-134,Cs-135, Cs-137

  18. Aespoe Hard Rock Laboratory. Final report of the first stage of the tracer retention understanding experiments

    Winberg, A. [Conterra AB, Uppsala (Sweden); Andersson, Peter [Geosigma AB, Uppsala (Sweden); Hermanson, Jan [Golder Grundteknik, Solna (Sweden); Byegaard, Johan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Chemistry; Cvetkovic, V. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Water Resources Engineering; Birgersson, Lars [Kemakta Konsult AB, Stockholm (Sweden)

    2000-03-15

    from its surrounding. The near proximity of the experimental array to the tunnel (10-15 m) implies a strong gradient (approximately 10%) in the structure, which has to be overcome and controlled during the experiments. A methodology for characterising fracture pore space using resin injection, excavation using large diameter coring and subsequent analysis with photo-microscopic and image analysis techniques was developed and tested at a separate site. The results show that epoxy resin can be injected over several hours, and that the estimated areal spread is in the order of square metres. The mean apertures of the two investigated samples were 239 and 266 microns, respectively. Assessment of spatial correlation show practical ranges in the order of a few millimetres. Performed tracer tests with conservative tracers in Feature A show that the feature is connected between its interpreted intercepts in the array. The parameters evaluated from the conservative tests; flow porosity, dispersivity and fracture conductivity are similar, indicating a relative homogeneity. Previous work has identified cationic tracers, featured by sorption through ion exchange, as the most suitable tracers for sorbing tracer experiments at ambient Aespoe conditions. Laboratory experiments on generic Aespoe material and site-specific material included batch sorption experiments on various size fractions of the geological material, and through diffusion experiments on core samples of variable length on a centimetre length scale. The sorbtivity was found to be strongly affected by the biotite content and the sorption was also found to increase with contact time. The sorbtivity was found to follow the relative order; {sup 22}Na{sup +} < {sup 47}Ca{sup 2+} {approx_equal} {sup 85}Sr{sup 2+} << {sup 86}Rb{sup +} {approx_equal} {sup 133}Ba{sup 2+} The field tracer tests, using essentially the same cocktail of sorbing tracers as in the laboratory, were found to show the same relative sorbtivity as seen

  19. ZZ FSXJ32, MCNP nuclear data library based on JENDL-3.2. ZZ FSXLIBJ33, MCNP nuclear data library based on JENDL-3.3

    1 - Description of program or function: - NEA-1424/03: JENDL-3.2 based MCNP library. Format: MCNP. Number of groups: Continuous energy cross section library. Nuclides: H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Hf, Ta, W, Pb, Bi, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm. Temperatures: 293 K, 600 K, 900 K, 1200 K, 1500 K, 2000 K. Origin: JENDL-3.2. The temperature-dependent continuous energy cross section library for MCNP, FSXJ32, was prepared from JENDL-3.2 for a variety of applications in the field of atomic energy. - NEA-1424/06: April 2005: This is the DVD version of ZZ-FSXJ32 NEA-1424/03. - NEA-1424/07: This version differs from version NEA-1424/05 in the following: Index files xsdir.fsxlb331 and xsdir.fsxlb332 have been updated, since atomic weights were missing for 23 nuclides. JENDL-3.3 based MCNP library. Format: MCNP. Number of groups: Continuous energy cross section library. Nuclides: 337 nuclides contained in JENDL-3.3. H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Ge-70, Ge-72, Ge-73, Ge-74, Ge-76, As-75, Se-74, Se-76, Se-77, Se-78, Se-79, Se-80, Se-82, Br-79, Br-81, Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, Kr-85, Kr-86, Rb-85, Rb-87, Sr-86, Sr-87, Sr-88, Sr-89, Sr-90, Y-89, Y-91, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Nb-94, Nb-95, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Tc-99, Ru-96, Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, Ru-103, Ru-104, Ru-106, Rh