A new “inotropic” pacemaker system is introduced for patients unable to increase heart rate in accordance with cardiocirculatory strain. An inotropic pacemaker senses the increase of heart contraction (inotropy) and uses this information to adjust the pacing rate. The fiber optic sensor, the optoelectrical unit and the re-closing of the control-loop are explained. The device is tested successfu...

The effects of sodium pump inhibition produced by exposure to the cardiac glycosides, ouabain or dihydroouabain, or by reduction in extracellular potassium to 1.0 mM, on contractile state and sodium-calcium exchange were studied in primary monolayer cultures of chick embryo ventricular cells. Ouabain, 10(-6)M, dihydroouabain, 5 X 10(-5)M, and extracellular potassium of 1.0 mM all induced simila...

extremely claustrophobic conditions, the nature of the patient's illness, and the requirements for patient compliance during the procedure followed by a rapid recovery. There is a paucity of information on how this can ideally be achieved. Propofol would appear to satisfy these requirements, but its unpredictable effects on involuntary movements precludes its use. The regimen suggested by Dr Gr...

Background: Selective phosphodiesterase (PDE3) inhibitors improve cardiac contractility and may use in congestive heart failure. However, their proarrhythmic potential is the most important side effect. Methods: In this research, we evaluated the potential cardiotonic activity of six new synthesized selective PDE3 inhibitors (6-hydroxy-4-methylquinolin-2(1H)-one derivatives) using the spontan...

We have studied relationships between the time-courses of lignocaine concentrations in arterial and coronary sinus blood and myocardial tissue, and negative inotropic effects on the myocardium, after i.v. bolus administration of 50-, 75- or 100-mg doses of lignocaine to conscious, chronically instrumented sheep. Peak arterial and coronary sinus blood lignocaine concentrations occurred 26-38 s b...

Calcitonin gene-related peptide (CGRP) is present in sensory nerve fibers in the heart and around peripheral arteries. On interaction with specific CGRP binding sites and activation of adenylate cyclase, CGRP causes vasodilation and has positive inotropic and chronotropic effects on the heart. In the present study, human CGRP I and II exerted positive inotropic effects on isolated human right a...

Cardiac electrophysiological heterogeneity related to the washout of acetylcholine (ACh) remains incompletely characterized. The aim of this study was to examine whether positive cardiac inotropic action is associated with electrophysiological heterogeneity between the atrium and the ventricle after ACh perfusion and washout. Epicardial monophasic action potentials (MAPs) from the right ventric...

The effect of adenosine on the function of the heart in Octopus vulgaris was studied using an isolated heait preparation. Bolus injections of adenosine or AMP (adenosine precursor) induced both positive chronotropic and inotropic effects. The maximum inotropic effect preceded the maximum chronotropic effect. The impermeable adenosine analogue 2-chloroadenosine elicited a similar effect, while t...

The effect of morphine and niet-enkephaline on the isometric contraction of rabbit papillary muscles was studied. The tested compounds produced a dose-dependent, stereospecific and naloxon-reversible negative inotropic effect indicating the existence of opiate receptors in cardiac muscle. A pretreatment of papillary muscles with the /3-blocking agent atenolol attenuated the negative inotropic a...

acrylamide gel. A highly active substance was isolated by ion-exchange chromatography on a 5 % cross-linked polymer ofacrylamide, NN'-methylenebisacrylamide and diethylaminoethyl methacrylate. 2. The initial gel-filtration experiments were carried out under a wide variety of conditions and resulted in the same yield of high-molecularweight and low-molecular-weight fractions with inotropic activ...