Costagliola, Ciro; dell'Omo, Roberto; Romano, Mario R; Rinaldi, Michele; Zeppa, Lucia; Parmeggiani, Francesco
Elevated intraocular pressure (IOP) has been recognized as the major risk factor for the development of glaucoma and a wide range of options are now available to reduce it: medical treatment, laser, filtering, or cyclodestructive surgery (alone or in combination). All these modalities act by decreasing eye pressure and, thereby, protecting the optic nerve head from a mechanic direct and/or vascular indirect insult. Topical medical therapy represents the first-choice treatment and, in most cases, it effectively controls IOP, avoiding the occurrence of further optic nerve damage. All medications lower IOP in two main ways: decreasing the production of aqueous humour or by increasing its outflow from the eye. Consequently, antiglaucoma drugs either suppress aqueous humour formation (beta-adrenergic antagonists, carbonic anhydrase inhibitors, and alpha-2-adrenergic agonists) or raise aqueous humour outflow throughout the conventional (e.g., pilocarpine) or uveoscleral (prostaglandin FP receptor agonists, and prostamides) route. In addition, fixed and unfixed combinations of antiglaucoma compounds have also been available for patients requiring more than one type of medication. This review, which is part one of two (please see Expert Opinion on Pharmacotherapy 10 (17)) briefly considers the characteristics of sympathomimetic, sympatholytics and parasympathomimetic commonly employed in the medical treatment of glaucoma, mainly the primary open-angle form, focusing the discussion on the clinical evidence supporting the use of these three classes of compound.
N. N. Nikitina
Full Text Available Aim. To evaluate the effect of imidasoline agonist, rilmenidine (Albarel, on 24-hour blood pressure (BP profile and autonomic regulation of cardiovascular system in young patients with arterial hypertension (HT and exogenous constitutional obesity (ECO.Material and methods. The study included 80 men aged 18-32 ( average age 20,5 years, including 34 patients with HT and normal body weight, 36 patients with HT and ECO, 10 healthy men as a control group. All hypertensive patients were treated with rilmenidine 1-2 mg daily during 12 weeks. BP 24-hour profile and heart rate variability (HRV were estimated before and after therapy.Results. Rilmenidine monotherapy resulted in significant reduction in average 24-hour, day-time and night-time BP as well as indices of BP loading in both groups. Indices of HRV proved the initial sympathetic overdrive among hypertensive patients especially among those with ECO. This sympathetic overdrive significantly reduced after 12 weeks of therapy.Conclusion. Rilmenidine effectively controls BP and reduces sympathetic system overdrive in young hypertensive patients with ECO.
Nap, Alexander; Balt, Jippe C.; Pfaffendorf, Martin; van Zwieten, Pieter A.
Objective To evaluate the facilitating effect of angiotensin II on sympathetic neurotransmission to quantitatively compare the sympatho-inhibitory potencies of the selective AT(1)-receptor antagonists losartan, irbesartan and telmisartan in the isolated rabbit thoracic aorta. Design To investigate
Leo, Anne-Marie; Mislovic, Branislav
This case report documents the inadvertent placement of an arterial cannula despite using realtime ultrasound to insert a peripheral venous cannula in a child with difficult venous access. The resultant limb ischemia was treated with an infraclavicular ultrasound-guided brachial plexus block as sympatholytic treatment.
Weerink, Maud A S; Struys, Michel M R F; Hannivoort, Laura N; Barends, Clemens R M; Absalom, Anthony R; Colin, Pieter
Dexmedetomidine is an alpha(2)-adrenoceptor agonist with sedative, anxiolytic, sympatholytic, and analgesic-sparing effects, and minimal depression of respiratory function. It is potent and highly selective for alpha(2)-receptors with an alpha(2):alpha(1) ratio of 1620:1. Hemodynamic effects, which
Dereli, Necla; Tutal, Zehra Baykal; Babayigit, Munire; Kurtay, Aysun; Sahap, Mehmet; Horasanli, Eyup
PURPOSE: Postoperative pain and nausea/vomitting (PNV) are common in laparoscopic cholecystectomy patients. Sympatholytic agents might decrease requirements for intravenous or inhalation anesthetics and opioids. In this study we aimed to analyze effects of esmolol on intraoperative anesthetic-postoperative analgesic requirements, postoperative pain and PNV. METHODS: Sixty patients have been included. Propofol, remifentanil and vecuronium were used for induction. Study groups were as follows;...
Arunima Chaudhuri; Nirmala G Borade
Menopause is associated with decreased heart rate variability, which is due to reduced parasympathetic or increased sympathetic outflow to the heart. Acute myocardial infarction may be accompanied by decreased heart rate variability. The causes of autonomic dysfunction in postmenopausal women may be multi-factorial i.e., dyslipidemia, increased body fat percentage, aging and loss of female sex hormones. The cardiac vagotonic and sympatholytic effects of estrogen can explain, at least in part,...
Nyberg, Michael Permin; Piil, Peter Bergmann; Egelund, Jon
Aging is associated with an altered regulation of blood flow to contracting skeletal muscle; however, the precise mechanisms remain unclear. We recently demonstrated that inhibition of cGMP-binding phosphodiesterase 5 (PDE5) increased blood flow to contracting skeletal muscle of older but not young......- and α2-adrenergic receptors. The level of the sympatholytic compound ATP was measured in venous plasma by use of the microdialysis technique. Sildenafil increased (P
Full Text Available Menopause is associated with decreased heart rate variability, which is due to reduced parasympathetic or increased sympathetic outflow to the heart. Acute myocardial infarction may be accompanied by decreased heart rate variability. The causes of autonomic dysfunction in postmenopausal women may be multi-factorial i.e., dyslipidemia, increased body fat percentage, aging and loss of female sex hormones. The cardiac vagotonic and sympatholytic effects of estrogen can explain, at least in part, why premenopausal women compared with postmenopausal women have a lower coronary heart disease incidence and mortality rate.
Parving, H H; Tarnow, L; Rossing, P
the ability to retard renal growth and possibly to attenuate mesangial entrapment of macromolecules and to attenuate the mitogenic effects of diverse growth factors. Calcium antagonists (except the old short-acting dihydropyridine drugs) reduce microalbuminuria and preserve kidney function in diabetic....... In a third group treated with sympatholytic drugs, more than 50% of the subjects had a doubling of their creatinine as compared to less than 10% in the two other groups mentioned above. However, long-term studies are needed to consolidate these findings and expand them to insulin-dependent diabetic patients...
This report reviews various management options for treatment-induced neuropathic pain in breast cancer. First-line options include tricyclic antidepressants and anticonvulsant drugs. Opioids should be prescribed according to published guidelines. Second-line treatments include lignocaine, mexiletine and ketamine. Sympatholytic therapies are available to patients with features of chronic regional pain syndrome. Anti-inflammatory agents are used for neurogenic inflammation. Surgical interventions are considered for refractory neuropathic pain. Interdisciplinary management is appropriate when persisting pain causes physical and psychosocial disabilities. Copyright (2004) Blackwell Science Pty Ltd
Mortensen, Stefan P.; Gonzalez-Alonso, Jose; Nielsen, Jens Jung
ATP and NE concentrations to gain insight into the interstitial and intravascular mechanisms by which ATP causes muscle vasodilation and sympatholysis. Leg hemodynamics and muscle interstitial nucleotide and norepinephrine (NE) concentrations were measured during: 1) femoral arterial ATP infusion (0......, respectively (Pcontracting muscle (Pmuscle, whereas interstitial NE concentrations increased similarly in both active...... and inactive muscles. These results suggest that the vasodilatory and sympatholytic effects of intraluminal ATP are mainly mediated via endothelial prinergic receptors. Intraluminal ATP and muscle contractions appear to modulate sympathetic nerve activity by inhibiting the effect of NE rather than blunting its...
Theofilos M Kolettis
Full Text Available Sympathetic activation during acute myocardial infarction is an important arrhythmogenic mechanism, but the role of central autonomic inputs and their modulating factors remain unclear. Using the in vivo rat-model, we examined the effects of clonidine, a centrally-acting sympatholytic agent, in the presence or absence of myocardial endothelin-B (ETB receptors. We studied wild-type (n=20 and ETB-deficient rats (n=20 after permanent coronary ligation, with or without pretreatment with clonidine. Cardiac rhythm was continuously recorded for 24 hours by implantable telemetry devices, coupled by the assessment of autonomic and heart failure indices. Sympathetic activation and arrhythmogenesis were more prominent in ETB-deficient rats during the early phase post-ligation. Clonidine improved these outcomes throughout the observation period in ETB-deficient rats, but only during the delayed phase in wild-type rats. However, this benefit was counterbalanced by atrioventricular conduction abnormalities and by higher incidence of heart failure, the latter particularly evident in ETB-deficient rats. Myocardial ETB-receptors attenuate the arrhythmogenic effects of central sympathetic activation during acute myocardial infarction. ETB-receptor deficiency potentiates the sympatholytic effects of clonidine and aggravates heart failure. The interaction between endothelin and sympathetic responses during myocardial ischemia/infarction and its impact on arrhythmogenesis and left ventricular dysfunction merit further investigation.
Full Text Available Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers are the basis of renoprotection therapy in chronic kidney disease. Parallel to decrease of glomerular filtration rate, there is an increase in the activity of the sympathetic nervous system, and the number of functioning nephrons reduces, which requires a change of treatment regimen. Reducing the risk of cardiovascular events on the background of increased hypertension probably dictates the need for a priority administration of sympatholytics, calcium channel blockers and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers withdrawal. ARAMONEL formula: ARAMONEL — AR(BA(CEIMO(xonidineNE(bivololL(ercandipine is changed to MNELD — M(oxonidineNE(bivololL(ercandipineD(iuretic that is used by us in recent years. Combined use of torsemide and xipamide is allowed. Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers withdrawal requires evidence, which may be obtained in STOP-ACEi trial.
Piil, Peter Bergmann
Oxygen delivery to skeletal muscle is regulated precisely to match the oxygen demand; however, with aging the regulation of oxygen delivery during exercise is impaired. The present thesis investigated mechanisms underlying the age-related impairment in regulation of blood flow and oxygen delivery...... to contracting skeletal muscle. Two studies, one acute exercise study and one large 8-week training intervention study, were conducted in young (18-28 years) and older (65-80 years) healthy, male subjects. In both studies, pharmacologic potentiation of the formation of cyclic guanosine monophosphate (c...... that improving sympatholytic capacity by training may be a slower process in older than in young men. In conclusion, this thesis provides new important knowledge related to the regulation of skeletal muscle blood flow in aging. Specifically, it demonstrates that changes in cGMP signaling is an underlying cause...
Thaning, Pia; Bune, Laurids T; Zaar, Morten
Sympathetic vasoconstriction is blunted in contracting human skeletal muscles (functional sympatholysis). In young subjects, infusion of adenosine and ATP increases blood flow, and the latter compound also attenuates α-adrenergic vasoconstriction. In patients with type 2 diabetes and age-matched ......Sympathetic vasoconstriction is blunted in contracting human skeletal muscles (functional sympatholysis). In young subjects, infusion of adenosine and ATP increases blood flow, and the latter compound also attenuates α-adrenergic vasoconstriction. In patients with type 2 diabetes and age......-matched healthy subjects, we tested 1) the sympatholytic capacity during one-legged exercise, 2) the vasodilatory capacity of adenosine and ATP, and 3) the ability to blunt α-adrenergic vasoconstriction during ATP infusion....
Claudio ede Lucia
Full Text Available Heart failure (HF is a chronic clinical syndrome characterized by the reduction in left ventricular (LV function and it represents one of the most important causes of morbidity and mortality worldwide. Despite considerable advances in pharmacological treatment, HF represents a severe clinical and social burden. Sympathetic outflow, characterized by increased circulating catecholamines (CAs biosynthesis and secretion, is peculiar in HF and sympatholytic treatments (as β-blockers are presently being investigated for the treatment of this disease. Adrenal gland secretes Epinephrine (80% and Norepinephrine (20% in response to acetylcholine stimulation of nicotinic cholinergic receptors on the chromaffin cell membranes. This process is regulated by adrenergic receptors (ARs: α2ARs inhibit CA release through coupling to inhibitory Gi-proteins, and βARs (mainly β2ARs stimulate CA release through coupling to stimulatory Gs-proteins. All ARs are G-protein-coupled receptors (GPCRs and GPCR kinases (GRKs regulate their signaling and function. Adrenal GRK2-mediated α2AR desensitization and downregulation are increased in HF and seem to be a fundamental regulator of CA secretion from the adrenal gland. Consequently, restoration of adrenal a2AR signaling through the inhibition of GRK2 is a fascinating sympatholytic therapeutic strategy for chronic HF. This strategy could have several significant advantages over existing HF pharmacotherapies (antiadrenergic, such as bAR-blockers minimizing side-effects on extra-cardiac tissues and reducing the chronic activation of the renin–angiotensin–aldosterone and endothelin systems.The role of adrenal ARs in regulation of sympathetic hyperactivity opens interesting perspectives in understanding pathophysiology of HF and identifying new potential therapeutic targets.
Champeroux, Pascal; Martel, Eric; Jude, Sebastien; Laigot, Christine; Laveissière, Arnaud; Weyn-Marotte, Andrée-Anne; Fowler, John Sinclair Lawrence; Maurin, Anne; Richard, Serge; Babuty, Dominique
Power spectral analysis of heart rate variability is a tool known to provide information of interest on the autonomic control of heart rate in human. However, its use and its conditions of application and interpretation for safety purposes are not well defined for cardiovascular safety pharmacology studies. Likewise, data of power spectral analysis of heart rate variability in cynomolgus monkeys, a species often appropriate for use as second non rodent species in preclinical safety programmes, are not available. This study was designed to evaluate the relevance of this biomarker in this non human primate species, and to compare results with those from beagle dogs under the conditions of safety evaluation studies. Power spectral analysis of heart rate variability was performed on data collected in both species by telemetry following a standard design for cardiovascular safety pharmacology studies. Various pharmacological agents were tested in order to compare the profile of responses in both species after modifying the autonomic nervous balance. Heart rate variability in cynomolgus monkeys is mainly driven by the parasympathetic nervous system as in beagle dogs although vagal tone is less than in dogs. Power spectral analysis of heart rate variability allows detection of interaction with the autonomic nervous system in both species in all investigated situations, i.e. sympatholytic/sympathomimetic and parasympatholytic/parasympathomimetic drug induced effects. However, due to species difference in the autonomic control of heart rate, cynomolgus monkeys are likely to be more sensitive than beagle dogs for assessment of sympatholytic properties. This study confirms that power spectral analysis of heart rate variability from data derived from ECG recordings in telemetry studies is applicable in cardiovascular safety pharmacology studies and may provide relevant information about possible interaction with the autonomic nervous system when new drug entities are evaluated
Vidrio, H; Hong, E
The sympatholytic and norepinephrine depleting drug 1-methyl-3-keto-4-phenylquinuclidinium bromide (MA540) possessed significant chronic antihypertensive activity in mecamylamine- and renal-hypertensive dogs. The compound was approximately four times more potent than guanethidine in the former model and three times as potent in the latter. MA540 reduced orthostatic blood pressure responses in unanesthetized rabbits, but was approximately ten times less potent than guanethidine. The quinuclidine derivative did not affect cardiac output, heart rate or stroke volume in anesthetized open chest dogs and moderately increased mean blood pressure and total peripheral resistance. It produced diuresis and saluresis in anesthetized dogs, but did not influence water or electrolyte urinary excretion in conscious rats. In the latter test, guanethidine produced antidiuresis and antisaluresis. It was concluded that MA540 is a potent, orally effective antihypertensive agent acting through adrenergic neuron blockade, that it lacks undesirable effects on cardiac and renal functions, and that compared with guanethidine, it is more potent in lowering blood pressure but less so in interfering with orthostatic cardiovascular reflexes.
Lam, Rex Pui Kin; Yip, Wai Lam; Wan, Chi Keung; Tsui, Matthew Sik Hon
Chemical restraint is often required to control agitation induced by methamphetamine. Dexmedetomidine is an α-2 adrenergic receptor agonist with sedative, analgesic, and sympatholytic properties. Its use in the emergency department (ED) to control methamphetamine-induced agitation has not been reported. To report two cases of methamphetamine-induced agitation successfully sedated with dexmedetomidine in the ED. The first case was a 42-year-old man with unstable emotion and violent behaviours after smoking methamphetamine. His agitation did not respond to a large cumulative dose of benzodiazepines (10mg of diazepam and 332mg of midazolam) administered over 48h and sedation was achieved with dexmedetomidine. The second case was a 38-year-old methamphetamine user with unstable emotion and recurrent episodes of agitation despite repeated doses of benzodiazepines, whose agitation was controlled with dexmedetomidine infusion. In both cases, dexmedetomidine apparently reduced the dose of benzodiazepines needed to achieve adequate sedation. Transient falls in blood pressure and slowing of the heart rate were noted, which resolved either spontaneously or after reducing the infusion rate without requiring drug treatment. Dexmedetomidine can be considered as an adjunct for chemical restraint when standard treatment fails to control the agitation induced by methamphetamine, but patient's hemodynamic state should be monitored closely during administration. Its efficacy and safety in the ED warrant further evaluation with prospective controlled trials. Copyright © 2016 Elsevier Inc. All rights reserved.
Kosaka, Toshimitsu; Ito, Hiroshi
The sympathetic nervous system plays an important role in the regulation of cardiovascular function both in healthy subjects and in patients with heart disease. Cardiac neurotransmission imaging allows in vivo noninvasive assessment of presynaptic storage, release and reuptake of neurotransmitters. Iodine-123 labeled metaiodobenzylguanidine (MIBG) is an analogue of the sympatholytic agent guanethidine and behaves in a manner that is similar to norepinephrine, a neurotransmitter of the sympathetic nervous system in the heart. Qualitative and quantitative assessment of MIBG uptake and washout kinetics has evaluated alterations of the cardiac sympathetic function in various heart diseases, such as cardiomyopathies, coronary artery disease, diabetic heart and arrhythmias. As reduced MIBG uptake has been related to the clinical indices of severity and prognosis, it can be used to evaluate the therapeutic effects on the cardiac sympathetic dysfunction. For example, angiotensin converting enzyme inhibitors and β-blockers which have been shown to improve functional capacity and prognosis in patients with heart failure, have been demonstrated to increase MIBG uptake and reduce its washout rate in these patients, indicating favorable effects on the sympathetic nervous system. Thus, MIBG imaging has become a promising noninvasive tool and a widely available modality for the assessment of prognosis and effects of medical therapy in various forms of cardiac pathology. The usefulness and recent advances of MIBG imaging in cardiology will be noted in this article. (author)
Abhijit S Nair
Full Text Available As per current recommendation, patients with acute ischemic stroke should be offered carotid endarterectomy (CEA within 24-72 hours. The same applies to patients with recurrent transient ischemic attacks (TIA. This time is usually less for hemodynamic optimization of patients who′ve suffered acute ischemic stroke. Hence′ they are hemodynamically labile and can have accelerated hypertension on induction/extubation. This can have disastrous outcomes. It is a common practice among anesthesiologists to avoid angiotensin converting enzyme(ACE inhibitors or angiotensin receptor blockers on the day of surgery. This also adds to hypertensive issues perioperatively. Dexmedetomidine is a wonderful drug which can be used during CEA. Due to its centrally mediated sympatholytic effect, it confers good hemodynamic control during induction, intraoperatively, and during extubation. We did a search on PubMed and Google for carotid endarterectomies done under general and locoregional anesthesia during which dexmedetomidine was used. The keywords used by us during the search were as follows: anesthesia, carotid endarterectomy, anesthesia. We also searched for use of dexmedetomidine infusion to attenuate hypertensive response to intubation and for providing stability in major surgeries like CABG, craniotomies, bariatric surgeries, and valve replacements.
Kalpana R Kulkarni
Full Text Available Stellate ganglion block (STGB is commonly indicated in painful conditions like reflex sympathetic dystrophy, malignancies of head and neck, Reynaud′s disease and vascular insufficiency of the upper limbs. The sympathetic blockade helps to relieve pain and ischaemia. Diagnostic STGB is usually performed with local anaesthetics followed by therapeutic blockade with steroids, neurolytic agents or radiofrequency ablation of ganglion. There is increasing popularity and evidence for the use of adjuvants like opioid, clonidine and N Methyl d Aspartate (NMDA receptor antagonist - ketamine - for the regional and neuroaxial blocks. The action of ketamine with sympatholytic block is through blockade of peripherally located NMDA receptors that are the target in the management of neuropathic pain, with the added benefit of counteracting the "wind-up" phenomena of chronic pain. We studied ketamine as an adjuvant to the local anaesthetic for STGB in 20 cases of peripheral vascular disease of upper limbs during the last 5 years at our institution. STGB was given for 2 days with 2 ml of 2% lignocaine + 8 ml of 0.25% bupivacaine, followed by block with the addition of 0.5 mg/kg of ketamine for three consecutive days. There was significant pain relief of longer duration with significant rise in hand temperature. We also observed complete healing of the gangrenous fingers in 17/19 patients.
Lovestrand, Donnamarie; Phipps, Steven; Lovestrand, Steven
Emergence agitation or delirium is a known phenomenon in the postanesthesia period. The underlying cause is not definitively understood. In a U.S. Army hospital's postanesthesia care unit, combat-related posttraumatic stress disorder (PTSD) can complicate interventions. Scant evidence-based research exists on the issue. By presenting case studies of 2 patients who underwent different surgical procedures, the authors argue that traditional modalities to reorient and calm patients experiencing emergence agitation who have PTSD are not shown to be effective. The first procedure demonstrates outcomes in a situation handled through traditional interventions. The second procedure demonstrates outcomes after incorporation of evidence-driven interventions. The authors conclude that best practice includes a proper identification of patients at risk of emergence agitation, a minimally stimulating environment, intraoperative sympatholytic therapy, and patient and staff education. Although the case studies presented support these principles, research is needed to provide stronger evidence. Military medical and research personnel can take the lead on this issue and be a source for improved outcomes and high-quality patient care.
The goal of this project is the development of radiopharmaceuticals which localize selectively in the normal myocardium and which can be used to assess myocardial perfusion and function with external detection systems. The availability of T1-201 as a myocardial imaging agent makes it possible to visualize compromised myocardium as an area of decreased radionuclide uptake. However, the long physical and biologic half-lives of this nuclide, as well as the low energy of its gamma emission and its cost, suggest a need to develop radiodiagnostic agents which have a similar myocardial distribution but employ a less expensive radioisotope with better decay properties. An approach developed in this proposal involves the use of cardioselective sympatholytic agents into which a suitable radionuclide can be incorporated. The two types of compounds to be investigated are the beta adrenoceptor antagonists and the catecholamine depleting agents. The radiolabeled products will be evaluated in normal and in experimentally infarcted animals, and their pharmacokinetics compared with those of T1-201. The most promising radiopharmaceuticals will subsequently be tested in larger animals having myocardial pathology
Full Text Available Stellate ganglion blockade (SGB is mainly used to relieve symptoms of neuropathic pain in conditions such as complex regional pain syndrome and has several potential complications. Noninvasive SGB performed using physical agent modalities (PAMs, such as light irradiation and electrical stimulation, can be clinically used as an alternative to conventional invasive SGB. However, its application protocols vary and its clinical efficacy remains controversial. This study investigated the use of noninvasive SGB for managing neuropathic pain or other disorders associated with sympathetic hyperactivity.We performed a comprehensive search of the following online databases: Medline, PubMed, Excerpta Medica Database, Cochrane Library Database, Ovid MEDLINE, Europe PubMed Central, EBSCOhost Research Databases, CINAHL, ProQuest Research Library, Physiotherapy Evidence Database, WorldWideScience, BIOSIS, and Google Scholar. We identified and included quasi-randomized or randomized controlled trials reporting the efficacy of SGB performed using therapeutic ultrasound, transcutaneous electrical nerve stimulation, light irradiation using low-level laser therapy, or xenon light or linearly polarized near-infrared light irradiation near or over the stellate ganglion region in treating complex regional pain syndrome or disorders requiring sympatholytic management. The included articles were subjected to a meta-analysis and risk of bias assessment.Nine randomized and four quasi-randomized controlled trials were included. Eleven trials had good methodological quality with a Physiotherapy Evidence Database (PEDro score of ≥6, whereas the remaining two trials had a PEDro score of <6. The meta-analysis results revealed that the efficacy of noninvasive SGB on 100-mm visual analog pain score is higher than that of a placebo or active control (weighted mean difference, -21.59 mm; 95% CI, -34.25, -8.94; p = 0.0008.Noninvasive SGB performed using PAMs effectively relieves
Lao, Hsuan-Chih; Tsai, Pei-Shan; Su, Jung-Yuan; Kwok, Tiew-Guan; Huang, Chun-Jen
Activation of sympathetic nervous system has a crucial role in mediating the pneumatic tourniquet inflation induced hyperdynamic response. Dexmedetomidine, a selective α(2)-adrenergic receptor agonist, has potent sympatholytic effects. We conducted this prospective, randomized, placebo-controlled, double-blinded study to elucidate the effects of dexmedetomidine on attenuating the tourniquet-induced hyperdynamic response during general anesthesia. We included a total of 72 healthy adult patients undergoing elective lower limb surgery. Under general anesthesia, patients were randomized to the dexmedetomidine or the control group (n = 36 in each group). The dexmedetomidine group received a loading dose of dexmedetomidine (0.8 μg·kg(-1) over 10 min) followed by continuous infusion of dexmedetomidine (0.4 μg·kg(-1).h(-1)) until tourniquet deflation. The control group received normal saline instead. We compared tourniquet-induced changes in hemodynamic parameters between groups to elucidate the effects of dexmedetomidine. Tourniquet inflation induced significant increases in hemodynamic parameters, including heart rate, systolic arterial pressure, mean arterial pressure, diastolic arterial pressure, rate pressure product, cardiac output, and stroke volume in the control group. The effects of tourniquet inflation on increasing hemodynamic parameters were significantly attenuated by dexmedetomidine: heart rate (P product (P < 0.001), and cardiac output (P = 0.001) of the dexmedetomidine group were significantly lower than those of the control group. However, the stroke volume of these groups was comparable. Dexmedetomidine attenuates tourniquet-induced hyperdynamic response in general anesthesia patients undergoing lower limb surgeries. Copyright © 2013 Elsevier Inc. All rights reserved.
El-Awady, G.A.; Abdelhalim, J.M.K.; Azer, M.S.
Dex medetomidine is a highly selective α2 agonist with anesthetic, analgesic and sympatholytic properties. Its neuromuscular effects in humans are unknown. This study evaluates the effect of dex medetomidine on neuromuscular block and hemodynamics during thiopental/ isoflurane anesthesia for patients with complex abdominal or pelvic surgery. Patients and methods: During thiopental/isoflurane anesthesia, the rocuronium infusion rate was adjusted in 20 complex surgery patients to maintain a stable first response (T1) in the train of four sequence of 50% ± 3 of the pre-rocuronium value. Dex medetomidine was then administered by infusion pump, targeting a plasma dex medetomidine concentration of 0.6 ng/dL for 45 min. The evoked mechanical responses of the adductor pollicis responses (T1 response and T4/T1 ratio), systolic blood pressure, diastolic blood pressure and heart rate (HR) were measured during the dex medetomidine infusion using repeated measures analysis of variance. Plasma levels ranged from 0.73 to 1.38 ng/mL. Results: T1 values decreased during the infusion from 55(ρ2 to 38±9 ((ρ< 0.05). T4/Tl values did not change during the infusion. Dex medetomidine increased SBP (ρ< 0.001) and decreased HR ((ρ< 0.05) (10 min median values) during the infusion compared with values before the infusion. This study demonstrated that dex medetomidine decreased T1, increased SBP and decreased HR during thiopental/isoflurane anesthesia. Conclusion: We conclude that dex medetomidine induced direct vasoconstriction may alter pharmacokinetics of rocuronium, therefore increasing plasma rocuronium concentration. Although these effects were statistically significant, further studies should be held for understanding and characterizing the peripheral vasoconstrictive effects of a2 agonists that allow better management and determination of drug dosing regimens
Dudenbostel, Tanja; Acelajado, Maria C.; Pisoni, Roberto; Li, Peng; Oparil, Suzanne; Calhoun, David A.
Refractory hypertension is an extreme phenotype of treatment failure defined as uncontrolled blood pressure (BP) in spite of ≥5 classes of antihypertensive agents, including chlorthalidone and a mineralocorticoid receptor antagonist. A prospective evaluation of possible mechanisms of refractory hypertension has not been done. The goal of this study was to test for evidence of heightened sympathetic tone as indicated by 24-hr urinary (U-) normetanephrine levels, clinic and ambulatory heart rate (HR), HR variability (HRV), arterial stiffness as indexed by pulse wave velocity (PWV), and systemic vascular resistance (SVR) compared to patients with controlled resistant hypertension. Forty-four consecutive patients, 15 with refractory and 29 with controlled resistant hypertension, were evaluated prospectively. Refractory hypertensive patients were younger (48±13.3 vs. 56.5±14.1 years, p=0.038) and more likely female (80.0 vs 51.9 %, p=0.047) compared to patients with controlled resistant hypertension. They also had higher U-normetanephrine levels (464.4±250.2 vs. 309.8±147.6 μg/24h, p=0.03), higher clinic HR (77.8±7.7 vs. 68.8±7.6 bpm, p=0.001) and 24-hr ambulatory HR (77.8±7.7 vs 68.8±7.6, p=0.0018), higher PWV (11.8±2.2 vs. 9.4±1.5 m/s, p=0.009), reduced HRV (4.48 vs. 6.11, p=0.03), and higher SVR (3795±1753 vs. 2382±349 dyne·sec·cm5·m2, p=0.008). These findings are consistent with heightened sympathetic tone being a major contributor to antihypertensive treatment failure and highlight the need for effective sympatholytic therapies in patients with refractory hypertension. PMID:25987662
Full Text Available Raynaud’s phenomenon (RP is a vasospastic disorder characterized by episodic color changes of blanching, cyanosis, and hyperemia in response to cold and/or emotional stress. Although most typically noted in the fingers, the circulation of the toes, ears, nose and tongue is also frequently affected. Population studies have shown that RP in adults is more common in women than men, with prevalence estimates ranging from 4% to 30%. Geographic variations in the prevalence reflect differences in climate. RP may be a primary or a secondary process. LeRoy and Medsger suggested criteria for primary RP: symmetric attacks, the absence of tissue necrosis, ulceration or gangrene, the absence of a secondary cause, negative antinuclear antibodies, normal nailfold capillaroscopy and a normal erythrocyte sedimentation rate. Secondary RP is characterized by an age of onset of more than 30 years, painful and asymmetric attacks, ischemic skin lesions, positive autoautoantibodies, capillaroscopic abnormalities and/or clinical features suggestive of connective tissue diseases (CTDs. Among the CTDs, systemic sclerosis has the highest frequency of RP. Finding a cause for RP requires a knowledge of the patient’s occupational, smoking, drug history, physical examination, nailfold capillaroscopy, routine laboratory tests and autoantibodies. Furthermore, RP should be distinguished from acrocyanosis, a condition characterized by continuous cyanosis of the hands or feet that is aggravated by cold temperature. The most important instruction to the patient is abstinence from any smoking, offending drugs should be discontinued, and abrupt changes in temperature. If these measures are inadequate, calcium-channel blockers are the most widely used (nifedipine 30 mg up to 90 mg daily. Alternatively, sympatholytic agent (prazosin, angiotensin II -receptor type I antagonist (losartan, selective sertonin-reuptake inhibitor (fluoxetine may be useful. In the severe cases the role of
Chamarthi, Bindu; Gaziano, J Michael; Blonde, Lawrence; Vinik, Aaron; Scranton, Richard E; Ezrokhi, Michael; Rutty, Dean; Cincotta, Anthony H
Type 2 diabetes (T2DM) patients, including those in good glycemic control, have an increased risk of cardiovascular disease (CVD). Maintaining good glycemic control may reduce long-term CVD risk. However, other risk factors such as elevated vascular sympathetic tone and/or endothelial dysfunction may be stronger potentiators of CVD. This study evaluated the impact of bromocriptine-QR, a sympatholytic dopamine D2 receptor agonist, on progression of metabolic disease and CVD in T2DM subjects in good glycemic control (HbA1c ≤ 7.0%). 1834 subjects (1219 bromocriptine-QR; 615 placebo) with baseline HbA1c ≤ 7.0% derived from the Cycloset Safety Trial (this trial is registered with ClinicalTrials.gov Identifier: NCT00377676), a 12-month, randomized, multicenter, placebo-controlled, double-blind study in T2DM, were evaluated. Treatment impact upon a prespecified composite CVD endpoint (first myocardial infarction, stroke, coronary revascularization, or hospitalization for angina/congestive heart failure) and the odds of losing glycemic control (HbA1c >7.0% after 52 weeks of therapy) were determined. Bromocriptine-QR reduced the CVD endpoint by 48% (intention-to-treat; HR: 0.52 [0.28-0.98]) and 52% (on-treatment analysis; HR: 0.48 [0.24-0.95]). Bromocriptine-QR also reduced the odds of both losing glycemic control (OR: 0.63 (0.47-0.85), p = 0.002) and requiring treatment intensification to maintain HbA1c ≤ 7.0% (OR: 0.46 (0.31-0.69), p = 0.0002). Bromocriptine-QR therapy slowed the progression of CVD and metabolic disease in T2DM subjects in good glycemic control.
Full Text Available In human cirrhosis, adrenergic hyperfunction causes proximal tubular fluid retention and contributes to diuretic-resistant ascites, and clonidine, a sympatholytic drug, improves natriuresis in difficult-to-treat ascites.To compare clonidine (aspecific α2-adrenoceptor agonist to SSP-002021R (prodrug of guanfacine, specific α2A-receptor agonist, both associated with diuretics, in experimental cirrhotic ascites.Six groups of 12 rats were studied: controls (G1; controls receiving furosemide and potassium canrenoate (G2; rats with ascitic cirrhosis due to 14-week CCl4 treatment (G3; cirrhotic rats treated (over the 11th-14th CCl4 weeks with furosemide and canrenoate (G4, furosemide, canrenoate and clonidine (G5, or diuretics and SSP002021R (G6. Three rats of each group had their hormonal status and renal function assessed at the end of 11th, 12th, 13th, and 14th weeks of respective treatments.Cirrhotic rats in G3 and G4 gained weight over the 12th-14th CCl4 weeks. In G4, brief increase in sodium excretion over the 11th-12th weeks preceded worsening of inulin clearance and natriuresis (diuretic resistance. In comparison with G4, the addition of clonidine (G5 or guanfacine (G6 to diuretics improved, respectively, sodium excretion over the 11th-12th CCl4 weeks, or GFR and electrolytes excretion over the 13th-14th CCl4 weeks. Natriuretic responses in G5 and G6 were accompanied by reduced catecholamine serum levels.α2A-receptor agonists restore glomerular filtration rate and natriuresis, and delay diuretic-resistant ascites in experimental advanced cirrhosis. Clonidine ameliorates diuretic-dependent natriuresis just for a short time.
of nitric oxide as well as by sympatholytic activities.
Dillon, Ryan C.; Palma, Jose-Alberto; Spalink, Christy L.; Altshuler, Diana; Norcliffe-Kaufmann, Lucy; Fridman, David; Papadopoulos, John; Kaufmann, Horacio
Objective Adrenergic crises are a cardinal feature of familial dysautonomia (FD). Traditionally, adrenergic crisis have been treated with the sympatholytic agent clonidine or with benzodiazepines, which can cause excessive sedation and respiratory depression. Dexmedetomidine is an α2A-adrenergic agonist with greater selectivity and shorter half-life than clonidine. We aimed to evaluate the preliminary effectiveness and safety of intravenous dexmedetomidine in the treatment of refractory adrenergic crisis in patients with FD. Methods Retrospective chart review of patients with genetically confirmed FD who received intravenous dexmedetomidine for refractory adrenergic crises. The primary outcome was preliminary effectiveness of dexmedetomidine defined as change in blood pressure (BP) and heart rate (HR) 1-hour after the initiation of dexmedetomidine. Secondary outcomes included incidence of adverse events related to dexmedetomidine, hospital and intensive care unit (ICU) length of stay, and hemodynamic parameters 12-hours after dexmedetomidine cessation. Results Nine patients over 14 admissions were included in the final analysis. At 1-hour after the initiation of dexmedetomidine, systolic BP decreased from 160±7 to 122±7 mmHg (p=0.0005), diastolic BP decreased from 103±6 to 65±8 (p=0.0003), and HR decreased from 112±4 to 100±5 bpm (p=0.0047). The median total adverse events during dexmedetomidine infusion was 1 per admission. Median hospital length of stay was 9 days (IQR, 3 – 11 days) and median ICU length of stay was 7 days (IQR, 3 – 11 days). Conclusions Intravenous dexmedetomidine is safe in patients with FD and appears to be effective to treat refractory adrenergic crisis. Dexmedetomidine may be considered in FD patients who do not respond to conventional clonidine and benzodiazepine pharmacotherapy. PMID:27752785
Johansson, Sofia; Lind, Morten Nikolaj
Aortic stenosis is a valvular lesion that poses several haemodynamic challenges for the anaesthesiologist. The use of central regional anaesthesia is traditionally regarded as contraindicated in patients with severe aortic stenosis due to its sympatholytic effect, potentially causing loss of vascular tone and ultimately diminished cardiac output. The aim of this paper was to review current literature to find evidence for or against the use of neuroaxial blockade in patients with aortic stenosis. We searched PubMed for relevant articles, using the following MeSH terms: "aortic valve stenosis", "epidural anesthesia", "spinal anesthesia" and "epidural analgesia". Only English language literature was included. Papers concerning aortic stenosis and obstetrical anaesthesia were excluded. There are no randomised clinical trials on the subject, and existing literature is extremely sparse. Four retrospective studies and eight case reports counting a total of ten patients were found. All report successful use of neuroaxial blockade in patients with aortic stenosis, without severe haemodynamic alterations. In addition, data indicate that postepidural analgesia improves outcome compared with conventional analgesia. To the best of our knowledge, there is no clinical evidence supporting the notion that central regional anaesthesia has any adverse effects on patients with aortic stenosis. Carefully managed neuroaxial blockade could become a useful alternative to general anaesthesia in this patient group. However, evidence is sparse and of questionable quality. Large prospective randomised clinical trials are required to establish best practise. Articles published in the DMJ are “open access”. This means that the articles are distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits any non-commercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Liao, Chun-De; Tsauo, Jau-Yih; Liou, Tsan-Hon; Chen, Hung-Chou; Rau, Chi-Lun
Stellate ganglion blockade (SGB) is mainly used to relieve symptoms of neuropathic pain in conditions such as complex regional pain syndrome and has several potential complications. Noninvasive SGB performed using physical agent modalities (PAMs), such as light irradiation and electrical stimulation, can be clinically used as an alternative to conventional invasive SGB. However, its application protocols vary and its clinical efficacy remains controversial. This study investigated the use of noninvasive SGB for managing neuropathic pain or other disorders associated with sympathetic hyperactivity. We performed a comprehensive search of the following online databases: Medline, PubMed, Excerpta Medica Database, Cochrane Library Database, Ovid MEDLINE, Europe PubMed Central, EBSCOhost Research Databases, CINAHL, ProQuest Research Library, Physiotherapy Evidence Database, WorldWideScience, BIOSIS, and Google Scholar. We identified and included quasi-randomized or randomized controlled trials reporting the efficacy of SGB performed using therapeutic ultrasound, transcutaneous electrical nerve stimulation, light irradiation using low-level laser therapy, or xenon light or linearly polarized near-infrared light irradiation near or over the stellate ganglion region in treating complex regional pain syndrome or disorders requiring sympatholytic management. The included articles were subjected to a meta-analysis and risk of bias assessment. Nine randomized and four quasi-randomized controlled trials were included. Eleven trials had good methodological quality with a Physiotherapy Evidence Database (PEDro) score of ≥6, whereas the remaining two trials had a PEDro score of <6. The meta-analysis results revealed that the efficacy of noninvasive SGB on 100-mm visual analog pain score is higher than that of a placebo or active control (weighted mean difference, -21.59 mm; 95% CI, -34.25, -8.94; p = 0.0008). Noninvasive SGB performed using PAMs effectively relieves pain of
Sansoè, Giovanni; Aragno, Manuela; Mastrocola, Raffaella; Parola, Maurizio
Sympathetic nervous system (SNS) activation decreases response to diuretics, but both α1-adrenoceptor agonists and sympatholytic α2-adrenoceptor agonists are recommended in the management of ascitic cirrhosis. We intend to compare the effects of increasing doses of clonidine (α2-agonist) vs. midodrine (α1-agonist) in advanced cirrhosis. Renal function, mean arterial pressure (MAP), and hormonal status were measured in rats with ascitic cirrhosis due to 13-week CCl(4) administration (groups G1-G5), in control rats (Gc), and in rats with ascitic cirrhosis untreated (G6) or treated with daily diuretics (0.5 mg/kg furosemide plus 2 mg/kg K(+) -canrenoate during the 11(th) -13(th) weeks of CCl(4)) (G7). G1-G5 cirrhotic rats received daily, during the 11(th)-13(th) CCl(4) weeks: clonidine 0.3 μg only (G1), diuretics + clonidine 0.2 (G2), 0.5 (G3) or 1 μg (G4), and diuretics + midodrine 1 mg/kg b.w. (G5). Cirrhotic rats in G1 or G2 had higher glomerular filtration rate, renal plasma flow and natriuresis than cirrhotic rats treated with diuretics (G7) (all P Midodrine did not improve the renal performance in ascitic rats treated with diuretics. In comparison to absolute cirrhotic controls (G6), MAP was lower in G4 and higher in G5 (all P < 0.05). Low-dose α2-agonists improve natriuresis and reduce SNS function and hyper-aldosteronism without affecting arterial pressure in experimental ascitic cirrhosis treated with diuretics. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
O'Connor, Christopher M; Fiuzat, Mona; Carson, Peter E; Anand, Inder S; Plehn, Jonathan F; Gottlieb, Stephen S; Silver, Marc A; Lindenfeld, JoAnn; Miller, Alan B; White, Michel; Walsh, Ryan; Nelson, Penny; Medway, Allen; Davis, Gordon; Robertson, Alastair D; Port, J David; Carr, James; Murphy, Guinevere A; Lazzeroni, Laura C; Abraham, William T; Liggett, Stephen B; Bristow, Michael R
Pharmacogenetics involves complex interactions of gene products affecting pharmacodynamics and pharmacokinetics, but there is little information on the interaction of multiple genetic modifiers of drug response. Bucindolol is a β-blocker/sympatholytic agent whose efficacy is modulated by polymorphisms in the primary target (β(1) adrenergic receptor [AR] Arg389 Gly on cardiac myocytes) and a secondary target modifier (α(2C) AR Ins [wild-type (Wt)] 322-325 deletion [Del] on cardiac adrenergic neurons). The major allele homozygotes and minor allele carriers of each polymorphism are respectively associated with efficacy enhancement and loss, creating the possibility for genotype combination interactions that can be measured by clinical trial methodology. In a 1,040 patient substudy of a bucindolol vs. placebo heart failure clinical trial, we tested the hypothesis that combinations of β(1)389 and α(2C)322-325 polymorphisms are additive for both efficacy enhancement and loss. Additionally, norepinephrine (NE) affinity for β(1)389 AR variants was measured in human explanted left ventricles. The combination of β(1)389 Arg+α(2C)322-325 Wt major allele homozygotes (47% of the trial population) was non-additive for efficacy enhancement across six clinical endpoints, with an average efficacy increase of 1.70-fold vs. 2.32-fold in β(1)389 Arg homozygotes+α(2C)322-325 Del minor allele carriers. In contrast, the minor allele carrier combination (13% subset) exhibited additive efficacy loss. These disparate effects are likely due to the higher proportion (42% vs. 8.7%, P = 0.009) of high-affinity NE binding sites in β(1)389 Arg vs. Gly ARs, which converts α(2C)Del minor allele-associated NE lowering from a therapeutic liability to a benefit. On combination, the two sets of AR polymorphisms 1) influenced bucindolol efficacy seemingly unpredictably but consistent with their pharmacologic interactions, and 2) identified subpopulations with enhanced (β(1)389 Arg
Christopher M O'Connor
Full Text Available Pharmacogenetics involves complex interactions of gene products affecting pharmacodynamics and pharmacokinetics, but there is little information on the interaction of multiple genetic modifiers of drug response. Bucindolol is a β-blocker/sympatholytic agent whose efficacy is modulated by polymorphisms in the primary target (β(1 adrenergic receptor [AR] Arg389 Gly on cardiac myocytes and a secondary target modifier (α(2C AR Ins [wild-type (Wt] 322-325 deletion [Del] on cardiac adrenergic neurons. The major allele homozygotes and minor allele carriers of each polymorphism are respectively associated with efficacy enhancement and loss, creating the possibility for genotype combination interactions that can be measured by clinical trial methodology.In a 1,040 patient substudy of a bucindolol vs. placebo heart failure clinical trial, we tested the hypothesis that combinations of β(1389 and α(2C322-325 polymorphisms are additive for both efficacy enhancement and loss. Additionally, norepinephrine (NE affinity for β(1389 AR variants was measured in human explanted left ventricles.The combination of β(1389 Arg+α(2C322-325 Wt major allele homozygotes (47% of the trial population was non-additive for efficacy enhancement across six clinical endpoints, with an average efficacy increase of 1.70-fold vs. 2.32-fold in β(1389 Arg homozygotes+α(2C322-325 Del minor allele carriers. In contrast, the minor allele carrier combination (13% subset exhibited additive efficacy loss. These disparate effects are likely due to the higher proportion (42% vs. 8.7%, P = 0.009 of high-affinity NE binding sites in β(1389 Arg vs. Gly ARs, which converts α(2CDel minor allele-associated NE lowering from a therapeutic liability to a benefit.On combination, the two sets of AR polymorphisms 1 influenced bucindolol efficacy seemingly unpredictably but consistent with their pharmacologic interactions, and 2 identified subpopulations with enhanced (β(1389 Arg
Chamarthi, Bindu; Cincotta, Anthony H
The concurrent use of an insulin sensitizer in type 2 diabetes mellitus (T2DM) patients with inadequate glycemic control on basal-bolus insulin may help improve glycemic control while limiting further insulin requirement. Bromocriptine-QR (B-QR), a quick release, sympatholytic, dopamine D2 receptor agonist therapy for T2DM, is a postprandial insulin sensitizer. This study evaluated the effect of B-QR on dysglycemia in T2DM subjects with suboptimal glycemic control on basal-bolus insulin plus metformin. The effect of once-daily morning administration of B-QR on dysglycemia was evaluated in 60 T2DM subjects derived from the Cycloset Safety Trial, with HbA1c >7% on basal-bolus insulin plus metformin at baseline, randomized to B-QR (N = 44) versus placebo (N = 16) and completed 12 weeks of study drug treatment. The analyses also included a subset of subjects on high-dose insulin (total daily insulin dose (TDID) ≥70 units; N = 36: 27 B-QR; 9 placebo). Subjects were well matched at baseline. After 12 weeks of B-QR treatment, mean % HbA1c decreased by -0.73% relative to baseline (p QR therapy resulted in % HbA1c reductions of -0.95 and -1.49 relative to baseline (p QR on HbA1c. The fasting plasma glucose (FPG) and TDID changes within each treatment group were not significant. More subjects achieved HbA1c ≤7 at 12 weeks with B-QR relative to placebo (36.4% B-QR vs 0% placebo, Fisher's exact 2-sided p = 0.003 in the entire cohort and 37% vs 0%, 2-sided p = 0.039 in the high-dose insulin subset). B-QR therapy improves glycemic control in T2DM subjects whose glycemia is poorly controlled on metformin plus basal-bolus insulin, including individuals on high-dose basal-bolus insulin. This glycemic impact occurred without significant change in FPG, suggesting a postprandial glucose lowering mechanism of action. Cycloset Safety Trial registration: ClinicalTrials.gov Identifier: NCT00377676.
Chamarthi, Bindu; Ezrokhi, Michael; Rutty, Dean; Cincotta, Anthony H
Type 2 diabetes mellitus (T2DM) is associated with a substantially increased risk of cardiovascular disease (CVD). Bromocriptine-QR (B-QR), a quick release sympatholytic dopamine D 2 receptor agonist, is a FDA-approved therapy for T2DM which may provide CVD risk reduction. Metformin is considered to be an agent with a potential cardioprotective benefit. This large placebo controlled clinical study assessed the impact of B-QR addition to existing metformin therapy on CVD outcomes in T2DM subjects. 1791 subjects (1208 B-QR; 583 placebo) on metformin ± another anti-diabetes therapy at baseline derived from the Cycloset Safety Trial, a 12-month, randomized, multicenter, placebo-controlled, double-blind study in T2DM, were included in this study. The primary CVD endpoint evaluated was treatment impact on CVD event rate, prespecified as a composite of time to first myocardial infarction, stroke, coronary revascularization, or hospitalization for unstable angina/congestive heart failure. Impact on glycemic control was evaluated as a secondary analysis. The composite CVD end point occurred in 16/1208 B-QR treated (1.3%) and 18/583 placebo treated (3.1%) subjects resulting in a 55% CVD hazard risk reduction (intention-to-treat, Cox regression analysis; HR: 0.45 [0.23-0.88], p = 0.028). Kaplan-Meier curves demonstrated a significantly lower cumulative incidence rate of the CVD endpoint in the B-QR treatment group (Log-Rank p = 0.017). In subjects with poor glycemic control (HbA1c ≥ 7.5) at baseline, B-QR therapy relative to placebo resulted in a significant mean %HbA1c reduction of -0.59 at week 12 and -0.51 at week 52 respectively (p QR 30%, placebo 3%; p = 0.003). These findings suggest that in T2DM subjects on metformin, BQR therapy may represent an effective strategy for reducing CVD risk. Cycloset Safety Trial registration: ClinicalTrials.gov Identifier: NCT00377676.
Andreev-Andrievskiy, A A; Popova, A S; Borovik, A S; Dolgov, O N; Tsvirkun, D V; Custaud, M; Vinogradova, O L
When tested on the treadmill mice do not display a graded increase of heart rate (HR), but rather a sharp shift of cardiovascular indices to high levels at the onset of locomotion. We hypothesized that under test conditions cardiovascular reaction to physical load in mice is masked with stress-associated HR increase. To test this hypothesis we monitored mean arterial pressure (MAP) and heart rate in C57BL/6 mice after exposure to stressful stimuli, during spontaneous locomotion in the open-field test, treadmill running or running in a wheel installed in the home cage. Mice were treated with β1-adrenoblocker atenolol (2mg/kg ip, A), cholinolytic ipratropium bromide (2mg/kg ip, I), combination of blockers (A+I), anxiolytic diazepam (5mg/kg ip, D) or saline (control trials, SAL). MAP and HR in mice increased sharply after handling, despite 3weeks of habituation to the procedure. Under stressful conditions of open field test cardiovascular parameters in mice were elevated and did not depend on movement speed. HR values did not differ in I and SAL groups and were reduced with A or A+I. HR was lower at rest in D pretreated mice. In the treadmill test HR increase over speeds of 6, 12 and 18m/min was roughly 1/7-1/10 of HR increase observed after placing the mice on the treadmill. HR could not be increased with cholinolytic (I), but was reduced after sympatholytic (A) or A+I treatment. Anxiolytic (D) reduced heart rate at lower speeds of movement and its overall effect was to unmask the dependency of HR on running speed. During voluntary running in non-stressful conditions of the home cage HR in mice linearly increased with increasing running speeds. We conclude that in test situations cardiovascular reactions in mice are governed predominantly by stress-associated sympathetic activation, rendering efforts to evaluate HR and MAP reactions to workload unreliable. Copyright © 2014 Elsevier Inc. All rights reserved.
Ben-Ami Bartal, Inbal; Shan, Haozhe; Molasky, Nora M. R.; Murray, Teresa M.; Williams, Jasper Z.; Decety, Jean; Mason, Peggy
Despite decades of research with humans, the biological mechanisms that motivate an individual to help others remain poorly understood. In order to investigate the roots of pro-sociality in mammals, we established the helping behavior test, a paradigm in which rats are faced with a conspecific trapped in a restrainer that can only be opened from the outside. Over the course of repeated test sessions, rats exposed to a trapped cagemate learn to open the door to the restrainer, thereby helping the trapped rat to escape (Ben-Ami Bartal et al., 2011). The discovery of this natural behavior provides a unique opportunity to probe the motivation of rodent helping behavior, leading to a deeper understanding of biological influences on human pro-sociality. To determine if an affective response motivates door-opening, rats receiving midazolam, a benzodiazepine anxiolytic, were tested in the helping behavior test. Midazolam-treated rats showed less helping behavior than saline-treated rats or rats receiving no injection. Yet, midazolam-treated rats opened a restrainer containing chocolate, highlighting the socially specific effects of the anxiolytic. To determine if midazolam interferes with helping through a sympatholytic effect, the peripherally restricted beta-adrenergic receptor antagonist nadolol was administered; nadolol did not interfere with helping. The corticosterone response of rats exposed to a trapped cagemate was measured and compared to the rats’ subsequent helping behavior. Rats with the greatest corticosterone responses showed the least helping behavior and those with the smallest responses showed the most consistent helping at the shortest latency. These results are discussed in terms of their implications for the interaction between stress and pro-social behavior. Finally, we observed that door-opening appeared to be reinforcing. A novel analytical tool was designed to interrogate the pattern of door-opening for signs that a rat’s behavior on one
Ben-Ami Bartal, Inbal; Shan, Haozhe; Molasky, Nora M R; Murray, Teresa M; Williams, Jasper Z; Decety, Jean; Mason, Peggy
Despite decades of research with humans, the biological mechanisms that motivate an individual to help others remain poorly understood. In order to investigate the roots of pro-sociality in mammals, we established the helping behavior test, a paradigm in which rats are faced with a conspecific trapped in a restrainer that can only be opened from the outside. Over the course of repeated test sessions, rats exposed to a trapped cagemate learn to open the door to the restrainer, thereby helping the trapped rat to escape (Ben-Ami Bartal et al., 2011). The discovery of this natural behavior provides a unique opportunity to probe the motivation of rodent helping behavior, leading to a deeper understanding of biological influences on human pro-sociality. To determine if an affective response motivates door-opening, rats receiving midazolam, a benzodiazepine anxiolytic, were tested in the helping behavior test. Midazolam-treated rats showed less helping behavior than saline-treated rats or rats receiving no injection. Yet, midazolam-treated rats opened a restrainer containing chocolate, highlighting the socially specific effects of the anxiolytic. To determine if midazolam interferes with helping through a sympatholytic effect, the peripherally restricted beta-adrenergic receptor antagonist nadolol was administered; nadolol did not interfere with helping. The corticosterone response of rats exposed to a trapped cagemate was measured and compared to the rats' subsequent helping behavior. Rats with the greatest corticosterone responses showed the least helping behavior and those with the smallest responses showed the most consistent helping at the shortest latency. These results are discussed in terms of their implications for the interaction between stress and pro-social behavior. Finally, we observed that door-opening appeared to be reinforcing. A novel analytical tool was designed to interrogate the pattern of door-opening for signs that a rat's behavior on one session
Patel Mayur B
Full Text Available Abstract Background Severe TBI, defined as a Glasgow Coma Scale ≤ 8, increases intracranial pressure and activates the sympathetic nervous system. Sympathetic hyperactivity after TBI manifests as catecholamine excess, hypertension, abnormal heart rate variability, and agitation, and is associated with poor neuropsychological outcome. Propranolol and clonidine are centrally acting drugs that may decrease sympathetic outflow, brain edema, and agitation. However, there is no prospective randomized evidence available demonstrating the feasibility, outcome benefits, and safety for adrenergic blockade after TBI. Methods/Design The DASH after TBI study is an actively accruing, single-center, randomized, double-blinded, placebo-controlled, two-arm trial, where one group receives centrally acting sympatholytic drugs, propranolol (1 mg intravenously every 6 h for 7 days and clonidine (0.1 mg per tube every 12 h for 7 days, and the other group, double placebo, within 48 h of severe TBI. The study uses a weighted adaptive minimization randomization with categories of age and Marshall head CT classification. Feasibility will be assessed by ability to provide a neuroradiology read for randomization, by treatment contamination, and by treatment compliance. The primary endpoint is reduction in plasma norepinephrine level as measured on day 8. Secondary endpoints include comprehensive plasma and urine catecholamine levels, heart rate variability, arrhythmia occurrence, infections, agitation measures using the Richmond Agitation-Sedation Scale and Agitated Behavior scale, medication use (anti-hypertensive, sedative, analgesic, and antipsychotic, coma-free days, ventilator-free days, length of stay, and mortality. Neuropsychological outcomes will be measured at hospital discharge and at 3 and 12 months. The domains tested will include global executive function, memory, processing speed, visual-spatial, and behavior. Other assessments include
Pharmacokinetic and pharmacodynamic effects of midodrine on blood pressure, the autonomic nervous system, and plasma natriuretic peptides: a prospective, randomized, single-blind, two-period, crossover, placebo-controlled study.
Lamarre-Cliche, Maxime; Souich, Patrick du; Champlain, Jacques de; Larochelle, Pierre
Midodrine is an alpha-agonist prodrug of desglymidodrine (DGM) that has been reported to be of clinical benefit in patients with neurocardiogenic syncope. Its effects may be mediated not only by its hypertensive properties but also by its neurohumoral influences independent of blood pressure (BP). The present study aimed to simultaneously characterize the effects of midodrine on BP, plasma catecholamines, plasma atrial natriuretic peptide (ANP), and power spectral analysis of heart rate (HR) in healthy volunteers. This was a prospective, randomized, single-blind, 2-period, crossover study in which a single, oral, 5-mg dose of midodrine was compared with placebo. The washout period between midodrine and placebo was 1 week. The study parameters included plasma DGM (as measured by high-performance liquid chromatography [HPLC]); systolic and diastolic BP (as measured with an oscillometric monitor); HR; plasma catecholamines (measured by HPLC); plasma ANP, also known as venous return (measured by a radio-immunoassay); and low- and high-frequency HR variation (calculated from computerized 5-minute electrocardiographic recordings). All study parameters were measured simultaneously 12 times just before and over a period of 8 hours after drug administration. Fifteen healthy nonsmoking male subjects (14 white, 1 black; mean [SD] age, 28.6 [4.7] years; weight, 74.5 [16.4] kg; seated BP, 109.9 [9.0]/73.6 [9.5] mm Hg; seated HR, 63.8 [8.4] bpm) were randomized. No significant effects of midodrine on BP were observed. At Cmax, midodrine decreased norepinephrine from 188.4 (30.6) to 162.5 (29.8) pg/mL (P = 0.011) and HR from 57.2 (7.3) to 54.9 (6.6) bpm (P = 0.022). A significant correlation was found between DGM concentration and HR ( varphi -0.61; P = 0.014). A DGM-related increase in plasma ANP (+29.6 [90.0] fmoL/mL) was observed. This study in healthy male volunteers found that midodrine has sympatholytic influences that are independent of BP but related to augmented venous
Ives, Stephen J; Park, Song Young; Kwon, Oh Sung; Gifford, Jayson R; Andtbacka, Robert H I; Hyngstrom, John R; Richardson, Russell S
What is the central question of this study? We sought to determine whether human skeletal muscle feed arteries (SFMAs) express TRPV 1 channels and what role they play in modulating vascular function. What is the main finding and its importance? Human SMFAs do express functional TRPV 1 channels that modulate vascular function, specifically opposing α-adrenergic receptor-mediated vasocontraction and potentiating vasorelaxation, in an endothelium-dependent manner, as evidenced by the α 1 -receptor-mediated responses. Thus, the vasodilatory role of TRPV 1 channels, and their ligand capsaicin, could be a potential therapeutic target for improving vascular function. Additionally, given the 'sympatholytic' effect of TRPV 1 activation and known endogenous activators (anandamide, reactive oxygen species, H + , etc.), TRPV 1 channels might contribute to functional sympatholysis during exercise. To examine the role of the transient receptor potential vanilloid type 1 (TRPV 1 ) ion channel in the vascular function of human skeletal muscle feed arteries (SMFAs) and whether activation of this heat-sensitive receptor could be involved in modulating vascular function, SMFAs from 16 humans (63 ± 5 years old, range 41-89 years) were studied using wire myography with capsaicin (TRPV 1 agonist) and without (control). Specifically, phenylephrine (α 1 -adrenergic receptor agonist), dexmedetomidine (α 2 -adrenergic receptor agonist), ACh and sodium nitroprusside concentration-response curves were established to assess the role of TRPV 1 channels in α-receptor-mediated vasocontraction as well as endothelium-dependent and -independent vasorelaxation, respectively. Compared with control conditions, capsaicin significantly attenuated maximal vasocontraction in response to phenylephrine [control, 52 ± 8% length-tension max (LT max ) and capsaicin, 21 ± 5%LT max ] and dexmedetomidine (control, 29 ± 12%LT max and capsaicin, 2 ± 3%LT max ), while robustly enhancing maximal