Low concentrations of UD-CG 212 enhance myocyte contractility by an increase in calcium responsiveness in the presence of inorganic phosphate.

Recent data show that UD-CG 212 in nanomolar concentrations increases myofibrillar Ca++ responsiveness of chemically skinned cardiac preparations in the presence of elevated inorganic phosphate. We studied the effects of UD-CG 212 on cell shortening of intact myocytes and in addition measured the intracellular calcium transients with the aid of INDO-1 fluorescence in the presence of 5 mM inorganic phosphate. The validity of our experimental system was first tested with the calcium channel opener Bay k 8644.

The novel 5-HT4 receptor antagonist DAU 6285 antagonizes 5-hydroxytryptamine-induced tachycardia in pigs.

The 5-HT4 receptor antagonist action of DAU 6285 was investigated in vivo in anesthetized pigs. DAU 6285 (0.3-3 mg/kg i.

Pimobendan increases survival of cardiomyopathic hamsters.

We investigated the effect of the new cardiotonic drug pimobendan on survival of hereditary cardiomyopathic hamsters. Untreated cardiomyopathic hamsters served as controls. A 50% mortality was observed after 280 days for the control group and after 318 days for the pimobendan-treated animals.

Hemodynamic profile of the cardiotonic agent pimobendan.

Pimobendan (UD-CG 115 BS) is a potent positive inotropic agent with vasodilatory properties. This hemodynamic profile was demonstrated in conscious rabbits chronically instrumented with Doppler flow probes. Pimobendan (10, 30, 100, and 300 micrograms/kg i.

Increase in calcium sensitivity of cardiac myofibrils contributes to the cardiotonic action of sulmazole.

The aim of this study was to investigate whether increasing calcium sensitivity of myofibrils plays a role in the positive inotropic activity of the cardiotonic agent sulmazole. We studied the effects of the stereoisomers of sulmazole on cardiac contractility in vivo and in vitro, arterial blood pressure, cardiac (Na-K)ATPase activity, cAMP/cGMP-phosphodiesterase activity of cardiac and smooth muscle tissue and calcium sensitivity of skinned myocardial fibres. Both stereoisomers of sulmazole were equipotent vasodilators in vivo and this can be explained by their equipotent cAMP- and cGMP-phosphodiesterase inhibitory activities in smooth muscle tissue.