Effects of three histaminergic compounds on function and oxygen consumption of isolated guinea-pig hearts.

First experiences in man indicate, that even in catecholamine-insensitive congestive cardiomyopathy a considerable improvement of myocardial function can be attained by the H2-receptor agonist impromidine. In an isolated, pressure-volume work performing guinea-pig heart preparation cardiac effects of three histaminergic compounds (Na,5-dimethylhistamine (HC1)2, 5-ethyl-Na-methyl-histamine (HC1)2, Na,Na-dimethyl-histamine (HC1)2) were examined. Influences on function and myocardial oxygen consumption were compared to those obtained by impromidine. Dose-response curves for the histamine derivatives were 1.7-2.5 orders of magnitude right of the impromidine curves. Maximal inotropic stimulation was greater for Na,5-dimethyl-histamine (HC1)2 than for impromidine. All compounds exhibited a high chronotropic effect and, at high concentrations, a net coronary dilating effect.