Search results for "sympathetic"
showing 10 items of 219 documents
A muscarinic inhibition of the noradrenaline release evoked by postganglionic sympathetic nerve stimulation
1969
1. The noradrenaline output from isolated rabbit hearts perfused with Tyrode solution was estimated fluorimetrically. The postganglionic sympathetic nerves of the heart were stimulated (10 shocks/sec; 1 msec) for three 1 min periods with intervals of 10 min. 2. The noradrenaline output evoked by 3 consecutive stimulation periods decreased exponentially. 3. Acetylcholine (10−9–10−6 g/ml) administered continuously one min before to one min after the second stimulation caused a dose-dependent reduction of the noradrenaline output evoked by the second stimulation to as low as 19% of the normal value. Acetylcholine in the concentrations applied did not cause a noradrenaline output by itself. 4. …
Inhibition by parasympathetic nerve stimulation of the release of the adrenergic transmitter
1970
Isolated rabbit atria were perfused with Tyrode solution containing (+)-amphetamine. Electrical stimulation of the right postganglionic sympathetic fibres caused an output of noradrenaline which was significantly decreased by simultaneous stimulation of the vagus nerves.
Subtypes of muscarinic receptor on cholinergic nerves and atrial cells of chicken and guinea-pig hearts
1988
1. Electrically driven chicken and guinea-pig atria were used to investigate the negative inotropic effects of the muscarinic agonists methacholine and acetylcholine (ACh). The release of ACh from isolated hearts into the perfusate in response to (preganglionic) vagal or (pre- and postganglionic) field stimulation was bioassayed on the guinea-pig ileum or determined by labelling with [3H]-choline. 2. Concentration-response curves for the negative inotropic effect of methacholine were shifted to the right by pirenzepine in various concentrations (0.03 to 10 mumol l-1). The pA2 values were 7.76 in chicken atria and 6.53 in guinea-pig atria. Pirenzepine and atropine antagonized the negative in…
Obesity and Outcomes in COVID-19: When an Epidemic and Pandemic Collide.
2020
Obesity has reached epidemic proportions in the United States and in much of the westernized world, contributing to considerable morbidity. Several of these obesity-related morbidities are associated with greater risk for death with coronavirus disease 2019 (COVID-19). Severe acute respiratory syndrome coronavirus 2 penetrates human cells through direct binding with angiotensin-converting enzyme 2 receptors on the cell surface. Angiotensin-converting enzyme 2 expression in adipose tissue is higher than that in lung tissue, which means that adipose tissue may be vulnerable to COVID-19 infection. Obese patients also have worse outcomes with COVID-19 infection, including respiratory failure, n…
Hypothalamic Apelin/Reactive Oxygen Species Signaling Controls Hepatic Glucose Metabolism in the Onset of Diabetes
2014
Aims: We have previously demonstrated that central apelin is implicated in the control of peripheral glycemia, and its action depends on nutritional (fast versus fed) and physiological (normal versus diabetic) states. An intracerebroventricular (icv) injection of a high dose of apelin, similar to that observed in obese/diabetic mice, increase fasted glycemia, suggesting (i) that apelin contributes to the establishment of a diabetic state, and (ii) the existence of a hypothalamic to liver axis. Using pharmacological, genetic, and nutritional approaches, we aim at unraveling this system of regulation by identifying the hypothalamic molecular actors that trigger the apelin effect on liver gluc…
Influence of capsaicin-sensitive afferent neurones on the acid secretory responses of the rat stomach in vivo.
1990
1. The influence of capsaicin-sensitive afferent neurones in modulating acid-secretory responses has been investigated in the continuously perfused stomach of the anaesthetized rat. 2. Ablation of primary afferent neurones, after systemic neonatal pretreatment with high doses of capsaicin, did not modify acid responses to direct stimuli of the oxyntic cell with histamine (5 mg kg-1), pentagastrin (20 micrograms kg-1) or carbachol (4 micrograms kg-1). 3. Acid responses to hypoglycaemia induced by insulin (0.3 iu kg-1) were not influenced by systemic capsaicin pretreatment or by acute coeliac ganglionectomy. Vagotomy abolished this secretory response. 4. The increase in acid output induced by…
Ischemic stroke increases heart vulnerability to ischemia-reperfusion and alters myocardial cardioprotective pathways
2018
Background and Purpose— For years, the relationship between cardiac and neurological ischemic events has been limited to overlapping pathophysiological mechanisms and common risk factors. However, acute stroke may induce dramatic changes in cardiovascular function. The aim of this study was to evaluate how prior cerebrovascular lesions affect myocardial function and signaling in vivo and ex vivo and how they influence cardiac vulnerability to ischemia-reperfusion injury. Methods— Cerebral embolization was performed in adult Wistar male rats through the injection of microspheres into the left or right internal carotid artery. Stroke lesions were evaluated by microsphere counting, tissue sta…
Ability of short-time Fourier transform method to detect transient changes in vagal effects on hearts: a pharmacological blocking study.
2006
Conventional spectral analyses of heart rate variability (HRV) have been limited to stationary signals and have not allowed the obtainment of information during transient autonomic cardiac responses. In the present study, we evaluated the ability of the short-time Fourier transform (STFT) method to detect transient changes in vagal effects on the heart. We derived high-frequency power (HFP, 0.20–0.40 Hz) as a function of time during active orthostatic task (AOT) from the sitting to standing posture before and after selective vagal (atropine sulfate 0.04 mg/kg) and sympathetic (metoprolol 0.20 mg/kg) blockades. The HFP minimum point during the first 30 s after standing up was calculated and…
Alcohol-Mediated Renal Sympathetic Neurolysis for the Treatment of Hypertension: The Peregrine™ Infusion Catheter.
2020
Renal sympathetic denervation using conventional non-irrigated radiofrequency catheters has potential technical shortcomings, including limited penetration depth and incomplete circumferential nerve damage, potentially impacting therapeutic efficacy. Against this background, second generation multi-electrode, radiofrequency and ultrasound renal denervation systems have been developed to provide more consistent circumferential nerve ablation. Irrigated catheters may allow deeper penetration while minimizing arterial injury. In this context, catheter-based chemical denervation, with selective infusion of alcohol, a potent neurolytic agent, into the perivascular space, may minimize endothelial…
A novel cholinergic-specific antigen (Chol-2) in mammalian brain.
1993
Three new antisera have been raised in sheep against cholinergic electromotor presynaptic plasma membranes prepared from the electric organs of the electric ray, Torpedo marmorata. They all recognized one or more cholinergic-specific antigens in the mammalian nervous system by the following criteria: they sensitized the cholinergic subpopulation of rat-brain synaptosomes--and only this subpopulation--to lysis by the complement system and, in an immunocytochemical study, selectively stained choline acetyltransferase-positive cholinergic neurons in the rat spinal cord. However, two of the three antisera failed to recognize Chol-1 alpha and -beta, two closely related minor gangliosides already…