Search results for "Inotrope"
showing 10 items of 58 documents
A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors.
1981
The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect in unrelated to beta-adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.
Cyclic AMP and cyclic GMP may play opposing roles in influencing force of contraction in mammalian myocardium.
1976
CYCLIC AMP and cyclic GMP have been suggested to play opposing regulatory roles in several biological systems1. Supporting evidence for the yin yang hypothesis of opposing biological regulation has been obtained in sympathetic ganglia2,3 and pyramidal neurones in the rat cerebral cortex4. In the mammalian heart, the role of cyclic AMP in mediating the positive inotropic response to catecholamines was advanced by the observation that the inotropic effect was preceded by an increase in cyclic AMP levels5. On the other hand, the levels of cyclic GMP were found to be increased after cholinergic stimulation6. In frog, oscillations of cyclic AMP7 and cyclic changes in the levels of cyclic AMP and…
�ber die positiv inotrope Wirkung von Dibutyryl-3?,5?-AMP an isolierten Rattenvorh�fen
1972
It is concluded that the positive inotropic action of DB-AMP—at least in isolated rat atria—may resemble that of adrenaline or theophylline in some points, e.g. with regard to its dependence on the [Ca]e. But as no positive inotropic effect could be observed in guinea-pig atria and as the mechanism by which DB-AMP augments contractile force remains obscure, the results are not thought to necessarily support the view that the effects of adrenaline or theophylline on contractile behaviour of mammalian cardiac muscle occur via cyclic AMP.
Electrical and mechanical activity of mammalian heart muscle fibres treated with papaverine
1977
The action of papaverine on electrical and mechanical activity was investigated in ventricular and atrial heart muscle fibres from guinea-pigs and cats. 1. Papaverine (10−5 M–5×10−5M) had positive, negative or no inotropic effects in ventricular preparations; positive inotropic effects were not observed after pretreatment of the animals with reserpine. In atrial preparations, papaverine (2×10−5M) had a positive inotropic effect that was independent of endogenously stored catecholamines. 2. The effects of isoprenaline and dibutyryl cyclic AMP were potentiated by papaverine (10−5 M–2×10−5M). 3. The action potential duration was always prolonged by papaverine in ventricular as well as in atria…
Effect of DB-c-AMP on mechanical characteristics of ventricular and atrial preparations of several mammalian species
1974
Conflicting results exist about the influence of cyclic N6-2′-O-dibutyryl-AMP (DB-c-AMP) on myocardial contractile force. The present study was designed to examine whether the positive inotropic action of DB-c-AMP is restricted to certain model preparations or whether it can be assumed to represent a more general effect of the drug. Therefore, the effects of DB-c-AMP on myocardial force and on various parameters of the isometric contraction curve were examined in isolated electrically driven (0.5–2Hz) ventricular and atrial preparations of several mammalian species (cat, rabbit, calf, sheep, rat and guinea-pig). The following results were obtained:
Does cyclic GMP mediate the negative inotropic effect of acetylcholine in the heart?
1977
DURING vagal stimulation the pacemaker activity of the heart is diminished. The reduction in heart rate is due to a release of acetylcholine (ACh) from the parasympathetic nerve terminals that increases the permeability of the myocardial cell membrane for potassium ions (for review see ref. 1). This is accompanied by a shortening of the action potential duration in atrial muscle and a diminished calcium uptake2, which in turn results in a negative inotropic effect. Voltage clamp experiments in mammalian atrial muscle have shown that with higher concentrations of ACh not only is the potassium current augmented but also the slow inward current of calcium is reduced3. It is not clear how the c…
Old and New Drugs for Treatment of Advanced Heart Failure.
2020
Background: Advanced heart failure (HF) is a progressive disease with high mortality and limited medical therapeutic options. Long-term mechanical circulatory support and heart transplantation remain goldstandard treatments for these patients; however, access to these therapies is limited by the advanced age and multiple comorbidities of affected patients, as well as by the limited number of organs available. Methods: Traditional and new drugs available for the treatment of advanced HF have been researched. Results: To date, the cornerstone for the treatment of patients with advanced HF remains water restriction, intravenous loop diuretic therapy and inotropic support. However, many patien…
Epinephrine Versus Norepinephrine for Cardiogenic Shock After Acute Myocardial Infarction
2018
IF 16.834 (2017); International audience; BACKGROUND Vasopressor agents could have certain specific effects in patients with cardiogenic shock (CS) after myocardial infarction, which may influence outcome. Although norepinephrine and epinephrine are currently the most commonly used agents, no randomized trial has compared their effects, and intervention data are lacking. OBJECTIVES The goal of this paper was to compare in a prospective, double-blind, multicenter, randomized study, the efficacy and safety of epinephrine and norepinephrine in patients with CS after acute myocardial infarction. METHODS The primary efficacy outcome was cardiac index evolution, and the primary safety outcome was…
Functional role of cholinoceptors and purinoceptors in human isolated atrial and ventricular heart muscle
1989
1. The effects of cholinergic and purinergic stimulation on action potential, force of contraction and 86Rb efflux were investigated in human atrial and ventricular heart muscle. 2. In atrial heart muscle, carbachol and (-)-N6-(R-phenyl-isopropyl)-adenosine (R-PIA) and 5'-(N-ethyl)-carboxamido-adenosine (NECA) evoked transient decreases of action potential duration and force of contraction; the steady-state effects on force of contraction were virtually identical to control values. In the presence of propranolol, steady-state values after carbachol, R-PIA or NECA amounted to about 50% of control values. 3. In ventricular heart muscle, carbachol, NECA and R-PIA did not significantly affect t…
Adrenaline, DB-c-AMP and myocardial 45Ca exchange. Comparative studies in rat and guinea-pig auricles
1973
The positive inotropic effect of adrenaline has been assumed to result from an increase in the intracellular level of c-AMP which, in turn, might enhance the permeability of the cardiac cell membrane to Ca2+. In order to further test this hypothesis, the effects of cyclic N6-2′-O-dibutyryl-adenosine-3′,5′-monophosphate (DB-c-AMP; 10−3 M) on mechanical performance, 45Ca uptake and total tissue calcium concentration were investigated in electrically stimulated (120 beats/min) left auricles isolated from female rats weighing 180–220 g. The experiments were performed in Tyrode solution containing 0.9 mM CaCl2; the duration of 45Ca exposure was 3–60 min. In this study, DB-c-AMP markedly enhanced…