Effects of the Calcium Agonistic Dihydropyridine Bay K 8644 on the Heart

Abstract

Besides their well documented therapeutic value the organic Ca²⁺-antagonists contributed a great deal to basic sciences since they triggered investigations leading to a better understanding of membrane physiology. Recently, it was shown that minor changes to the nifedipine molecule (Fig. 1) lead to dihydropyridine-derivatives with pharmacological properties just opposite to the classical calcium antagonistic dihydropyridines: Bay K 8644 (methyl 1,4-Dihydro-2, 6-dimethyl-3-nitro-4-(2-trifluoromethylophenyl)- pyridine-5-carboxylate) is a calcium agonistic dihydropyridine which increases calcium influx into the cell (Schramm et al 1983; Meyer et al. 1985) and by this mechanism increases force of contraction both of smooth and of heart muscle. Apart from offering a new tool for basic research it may introduce a new class of potent positive inotropic drugs. This report is to summarize findings with Bay K 8644 as obtained both in vivo and in vitro with respect to its effects on the heart.