We studied the influence of acidosis on the positive inotropic effect of UD-CG 212 Cl (4,5-dihydro-6-[2-(4-hydroxyphenyl)-1H-benzimidazole-5-yl]-5-methyl-3(2H)-pyridazinone), an active metabolite of pimobendan, in canine ventricular trabeculae loaded with aequorin. The positive inotropic effect of UD-CG 212 Cl was markedly suppressed under acidotic conditions. The maximal contractile response t...

The aim of the present study was to determine possible inotropic effects mediated by endothelin ET(A) and ET(B) receptors in human myocardial trabeculae from the right atrium and the left ventricle. Isolated trabeculae from human hearts were paced at 1.0 Hz in tissue baths, and changes in isometric contractile force upon exposure to agonist were studied. Endothelin-1 (ET-1) and ET-3 had a stron...

Clinical Use of Digitalis Glycosides The potential benefit of digoxin therapy in heart failure patients is thought to be related to its positive inotropic effect that increases cardiac output and thereby decreases ventricular filling pressures.2 Although digoxin is undoubtedly an inotropic agent in tissue preparations,3 this effect, in contrast to other inotropic agents, is not consistently tra...

OBJECTIVE To identify the effects of altered ventricular activation during dobutamine stress on left ventricular function in normal subjects and in patients with coronary artery disease, and to distinguish these from an inotropic response. DESIGN Prospective analysis of 12 lead ECG and echocardiogram at rest and at peak stress. SETTING Tertiary referral centre for cardiac disease equipped w...

The action of a novel cardiotonic agent N-hydroxy-5,6-dimethoxy-benzo[b]thiophene-2-carboximide hydrochloride (Org 30029) on intracellular aequorin light transients and isometric contractions was investigated in isolated canine ventricular trabeculae. The positive inotropic effect of Org 30029 (30 microM-3 mM) was consistently associated with prolongation of the duration of contraction and an i...

In chronically instrumented, conscious dogs, rapid injection of equihypotensive doses of three calcium channel-blocking agents, verapamil (250 micrograms/kg), diltiazem (200 micrograms/kg) and nifedipine (50 micrograms/kg), produced disparate chronotropic and inotropic responses. Although they all decreased mean arterial pressure by about 10%, heart rate (93 +/- 4 beats/min) was markedly increa...

BACKGROUND AVE0118 (2'-{[2-(4-Methoxy-phenyl)-acetylamino]-methyl}-biphenyl-2-carboxylic acid (2-pyridin-3-yl-ethyl)-amide) blocks atrial ultrarapid delayed rectifier currents (I(Kur)) and prolongs the atrial action potential (AP) plateau without affecting ventricular repolarisation. In patients with atrial contractile dysfunction due to atrial tachyarrhythmias, this response might increase atr...

Classic inotropic agents provide short-term haemodynamic improvement in patients with heart failure, but their use has been associated with poor prognosis. A new category of inotropic agents, the Ca(2+) sensitizers, may provide an alternative longer lasting solution. Levosimendan is a relatively new Ca(2+) sensitizer which offers haemodynamic and symptomatic improvement by combining a positive ...

The inotropic, chronotropic, and vasodilatory effects of five commonly used cyclic adenosine 3',5'-monophosphate (cAMP)-modulating agents were evaluated. Hemodynamic functions were measured continuously in isoflurane-anesthetized cats during infusion of the following: dobutamine (DOB; 2.5, 5 and 10 microg/kg/min; n=8), dopamine (DOP; 1.25, 2.5, 5 and 10 microg/kg/min; n=5), milrinone (MIL; 2.5,...

The effects of piretanide and furosemide on systemic arterial blood pressure and heart rate were examined in the anesthetized dog and the effects on atrial rate and contractile force were assessed in isolated atrial muscle perfused with heparinized arterial blood from a donor dog. When piretanide was administered intravenously to intact dogs, the depressor and bradycardic responses were produce...