Search results for "Sympatholytics"
showing 10 items of 33 documents
Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isol…
2018
[EN] A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1 mu M), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activatio…
The effect of balloon dilatation on post-stenotic myocardial perfusion before and after stimulation of coronary flow reserve: evaluation by the densi…
1988
From densitometric evaluation of digital subtraction cineangiocardiograms the parameter 'Mean Rise Time' (MRT), defined as the time from the onset of local myocardial contrast medium opacification to the point of maximal opacification can be derived; this parameter revealed a close correlation with the results on myocardial perfusion obtained by Thallium-201 scintigraphy. A prolonged 'Mean Rise Time' was indicative of an impairment of myocardial perfusion. We have developed a heart-phase gated real-time digitization procedure and computer-supported method for the densitometric estimation of the MRT to obtain information about the effect of coronary balloon dilatation on myocardial perfusion…
The Effects of Sympathetic Inhibition on Metabolic and Cardiopulmonary Responses to Exercise in Hypoxic Conditions.
2015
Objective Pre-exertion skeletal muscle glycogen content is an important physiological determinant of endurance exercise performance: low glycogen stores contribute to premature fatigue. In low-oxygen environments (hypoxia), the important contribution of carbohydrates to endurance performance is further enhanced as glucose and glycogen dependence is increased; however, the insulin sensitivity of healthy adult humans is decreased. In light of this insulin resistance, maintaining skeletal muscle glycogen in hypoxia becomes difficult, and subsequent endurance performance is impaired. Sympathetic inhibition promotes insulin sensitivity in hypoxia but may impair hypoxic exercise performance, in p…
Beta-adrenergic blocking activity and haemodynamic effects in man of K� 1313, a new beta-adrenergic antagonist
1971
The beta-adrenergic blocking activity and haemodynamic effects of o-[2-hydroxy-3-(isopropylamino)-propoxy]-benzonitril (Ko 1313) have been studied in 22 patients. Antagonism of isoproterenol-induced tachycardia was used as a measure of the beta-adrenergic blocking activity. Ko 1313 1.0 mg had its maximum beta-adrenoceptor blocking effect 5–30 min after intravenous injection. Ko 1313 10.0 mg produced maximum betablockade 1–4 h after oral administration. 1.0 mg Ko 1313 injected intravenously had approximately the same beta-adrenergic blocking effect as 1.0 mg propranolol also given intravenously. After intravenous administration Ko 1313 was 3–4 times as potent as the same dose given orally. A…
The 5-HT and alpha-adrenoceptor antagonist effect of four benzylisoquinoline alkaloids on rat aorta.
1998
Abstract The action of four benzylisoquinoline alkaloids (two aporphines—glaucine and apomorphine, a benzylisoquinoline—papaverine and a bisbenzyltetrahydroisoquinoline—antioquine) on 5-HT-induced contraction in rat thoracic aorta has been examined and compared with that of the control drugs: ketanserin, nifedipine, prazosin and phentolamine. The relaxant action on 5-HT-induced contraction was contrasted with that on the contraction induced by noradrenaline and KCl. The results obtained with control drugs show that ketanserin has clear selectivity for 5-HT receptors, whereas prazosin and phentolamine have high selectivity for the α1-adrenoceptor and nifedipine seems to have a more potent ef…
Glycopyrronium bromide blocks differentially responses mediated by muscarinic receptor subtypes.
1993
To analyse the potency of glycopyrronium bromide in blocking responses mediated via subtypes of muscarinic receptors in vitro, we tried to determine its equilibrium dissociation constants at prejunctional muscarinic receptors inhibiting the twitch response of rabbit vas deferens (presumed M1 type), at M2 (paced at left atria), M3 (guinea pig ileum) muscarinic receptor subtypes and at the muscarinic receptor of the rabbit iris sphincter (not M1-M4, not m5). Glycopyrronium bromide shifted to the right the curve for inhibition of the twitch response induced by the agonist McN-A-343, and the methacholine-induced curves for inhibition of rat atrial contraction, and for tonic contraction of guine…
Antispasmodic effect of 4'-methylepigallocatechin on guinea pig ileum.
2012
AbstractThe antispasmodic effect of 4′-methylepigallocatechin (MEC), which was isolated from Maytenus rigida Mart (Celestraceae), was investigated in vitro in guinea pig intestinal segments. In the isolated ileum, MEC (1 nM–100μM) did not modify the ileal spontaneous tonus or the electrically elicited contractions. MEC (8μM) significantly (p<0.01) reduced the submaximal contractions induced by histamine (2μM), carbachol (100μM) and BaCl2 (0.03M). An additive relaxing action (p<0.001) was observed by co-incubation of verapamil (10 nM) and MEC (8μM). Although MEC (1nM–100μM) did not modify the contractions elicited by 60mM KCl, it significantly reduced the CaCl2 contractile response without c…
Transmural myocardial ischaemia complicating recovery after dobutamine-atropine stress echocardiography in patients with non-significant coronary art…
2011
In the proposed selection of cases, traditional imaging is integrated with contemporary diagnostic tools available in the cath-lab to navigate the potential mechanisms underlying a very rare complication occurring in the recovery phase of dobutamine-atropine stress echocardiography. The data, collected in a time frame of nearly 15 years, provide interesting elements to possibly evolve from speculative considerations to plausible confirmation of the candidate pathophysiological mechanism mediating the occurrence of transmural myocardial ischaemia after beta-blockers administration.
Antimuscarinic action of quinidine on the heart? A study in myocardial preparations from cat hearts
1984
Quinidine exerts anticholinergic effects which have been ascribed to atropine-like properties of the drug. We have examined the effects of acetylcholine on the force of contraction in isolated heart muscle preparations from cats and compared the inhibitory effects of atropine with those of quinidine. The effects of acetylcholine were antagonized competitively in the presence of atropine. The Schild-plot yielded a straight line; the slope was not significantly different from unity. In the presence of quinidine, the concentration-response curve of acetylcholine was shifted to the right as with atropine, however, the Schild-plot yielded a regression line which was not linear; the slope was sta…
The effects of histamine on the isolated mouse uterus
2000
1. A study is made of the contractile and relaxant effects, and mechanism of action, of histamine on isolated uterus from mice treated with diethylstilboestrol, employing acetylcholine and adrenaline as contractile and relaxant standard agents. 2. Concentration-response curves for histamine agonists were obtained in the absence and presence of selective histaminergic blocking drugs (clemizole, ranitidine and thioperamide) and indomethacin. A number of experiments were carried out in uterus from reserpinised mice. Concentration-response curves for acetylcholine and adrenaline were also obtained in the absence and presence of their selective antagonist (atropine and propranolol). 3. In isolat…