Search results for "Chronotropic"
showing 10 items of 22 documents
Expression and Signaling of β-Adrenoceptor Subtypes in the Diabetic Heart.
2020
Diabetes is a chronic, endocrine disorder that effects millions of people worldwide. Cardiovascular complications are the major cause of diabetes-related morbidity and mortality. Cardiac β1- and β2-adrenoceptor (AR) stimulation mediates positive inotropy and chronotropy, whereas β3-AR mediates negative inotropic effect. Changes in β-AR responsiveness are thought to be an important factor that contributes to the diabetic cardiac dysfunction. Diabetes related changes in β-AR expression, signaling, and β-AR mediated cardiac function have been studied by several investigators for many years. In the present review, we have screened PubMed database to obtain relevant articles on this topic. Our s…
PACAP induces bradycardia in guinea-pig heart by stimulation of atrial cholinergic neurones
1996
Based on previous studies which indicated that pituitary adenylate cyclase activating peptide (PACAP) acts as a positive inotropic and chronotropic substance in different species via the cAMP signal transduction pathway, the objective of the present work was to investigate cAMP-regulated myocardial key proteins in response to PACAP in isolated ventricular cells of the guinea pig. Surprisingly, the two molecular forms of PACAP, PACAP(1-27) and PACAP(1-38), showed no effect on intracellular cAMP-levels, L-type Ca2+ channel current or phosphorylation of troponin inhibitor (TnI) and phospholamban (PLB). Additionally, inotropy of isolated guinea-pig ventricular strips was not affected by the neu…
The COGNITION Study Rationale and Design: Influence of Closed Loop Stimulation on Cognitive Performance in Pacemaker Patients
2008
Background: Several studies showed the beneficial effect of pacemaker implantation on cognitive performance in patients with bradycardia. But it has never been investigated if patients with chronotropic incompetence may improve their cognitive performance if treated by a rate-adaptive system reacting to mental stress in comparison to the most frequently used accelerometer-driven pacing. Methods: The randomized, single-blind, multicenter COGNITION study evaluates if closed loop stimulation (CLS) offers incremental benefit in the speed of cognitive performance and the overall well-being of elderly patients with bradycardia compared with accelerometer-based pacing. Four hundred chronotropicall…
Atropine-resistant effects of the muscarinic agonists McN-A-343 and AHR 602 on cardiac performance and the release of noradrenaline from sympathetic …
1974
Abstract 1 The effects of 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343) and N-benzyl-3-pyrrolidyl acetate methobromide (AHR 602) on cardiac performance and noradrenaline release from terminal sympathetic fibres were measured in isolated perfused hearts of rabbits. 2 In the presence of sufficient atropine to block muscarinic receptors, high concentrations of McN-A-343 and AHR 602 caused no cardiac stimulation and there was no increase in the resting output of noradrenaline into the perfusates. 3 McN-A-343 and AHR 602 increased both the mechanical responses and the transmitter overflow evoked by electrical stimulation of the sympathetic nerves (SNS) but inhibi…
3,4-trans-4-Aryl-3-(1-pyridinio)-1,2,3,4-tetrahydropyridine-6-thiolates—new group of potential cardiotonic drugs
2005
Abstract 3,4- trans -4-Aryl-3-(1-pyridinio)-1,2,3,4-tetrahydropyridine-6-thiolates 6 – 11 were prepared by a Michael reaction of N -acetonylpyridinium chloride with 3-aryl-2-cyanothioacrylamides or by a one-pot three-carbon condensation of N -acetonylpyridinium chloride, aromatic aldehyde and 2-cyanothioacetamide, and their cardiotonic properties were studied. 3,4- trans -5-cyano-2-hydroxy-2-methyl-4-(3-nitrophenyl)-3-(1-pyridinio)-1,2,3,4-tetrahydropyridine-6-thiolate 8 was considered as a lead compound in this series since it in vitro experiments (spontaneously beating rat atria) showed a cardiotonic activity similar to that of milrinone 2 , however compound 8 induced activity at lover co…
Exercise, Chronotropic and Inotropic Capacity in Athletes with Different Training Programmes
2020
Abstract Amateur sport has significant influence on peoples’ physical activity and affects the prevalence of non-communicable diseases. The population of competing amateur athletes has not been sufficiently studied, and there is a huge gap between functional results of untrained individuals and professional athletes. The aim of the study was to evaluate the exercise capacity and chrono-tropic, inotropic capacity in amateur athletes with different training programmes, as assessed by cardiopulmonary exercise testing. In a longitudinal prospective study, 600 amateur athletes who performed high dynamic load sports, according to the Mitchell Classification of Sports, were assessed. The individua…
Vascular resistance arm of the baroreflex: methodology and comparison with the cardiac chronotropic arm.
2020
Baroreflex response consists of cardiac chronotropic (effect on heart rate), cardiac inotropic (on contractility), venous (on venous return) and vascular (on vascular resistance) arms. Because of its measurement simplicity, cardiac chronotropic arm is most often analysed. The aim was to introduce a method to assess vascular baroreflex arm, and to characterize its changes during stress. We evaluated the effect of orthostasis and mental arithmetics (MA) in 39 (22 female, median age: 18.7 yrs.) and 36 (21 female, 19.2 yrs.) healthy volunteers, respectively. We recorded systolic and mean blood pressure (SBP and MBP) by volume-clamp method and R-R interval (RR) by ECG. Cardiac output (CO) was re…
The lack of the effect of DA-1 and DA-2 dopamine agonists on the isolated guinea-pig atria.
1987
1 The effects of dopamine and both DA-1 and DA-2 dopamine receptor agonists have been studied on the contractile force of electrically driven guinea-pig left atria and frequency of spontaneously beating right atria. 2 Pretreatment of animals with reserpine caused a parallel rightward shift of the concentration-response curve to dopamine of either preparation. 3 Propranolol, but not domperidone, shifted to the right the dose-response curve for the positive inotropic and chronotropic effects of dopamine. 4 Neither apomorphine, fenoldopam, bromocriptine nor piribedil had effects on the frequency and contractile force of the isolated guinea-pig atria. 5 These results suggest that DA-1 and DA-2 …
Effects of a phycotoxin, okadaic acid, on oyster heart cell survival
2008
Okadaic acid (OA) is a dinoflagellate toxin which accumulates in shellfish producing diarrhetic shellfish poisoning (DSP) in humans. It was found that OA is a highly selective inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A) which produces a marked increase in phosphorylation of several proteins, including p38 mitogen-activated protein (MAP) kinase. The cytotoxicity attributed to OA and the effects on p38 MAP kinase and calcium current were examined in the oyster Crassostrea gigas in this study. Data showed that p38 MAP kinase is strongly expressed in oyster heart and that OA bioaccumulated in cultured heart cells. Hence the effects of OA was tested in vitro and in vivo on oyste…
Paradoxical effect of increased diastolic Ca(2+) release and decreased sinoatrial node activity in a mouse model of catecholaminergic polymorphic ven…
2012
Background— Catecholaminergic polymorphic ventricular tachycardia is characterized by stress-triggered syncope and sudden death. Patients with catecholaminergic polymorphic ventricular tachycardia manifest sinoatrial node (SAN) dysfunction, the mechanisms of which remain unexplored. Methods and Results— We investigated SAN [Ca 2+ ] i handling in mice carrying the catecholaminergic polymorphic ventricular tachycardia–linked mutation of ryanodine receptor (RyR2 R4496C ) and their wild-type (WT) littermates. In vivo telemetric recordings showed impaired SAN automaticity in RyR2 R4496C mice after isoproterenol injection, analogous to what was observed in catecholaminergic polymorphic ventricul…