EFFECT OF BERAPROST SODIUM ON CHANGES IN ACTION-POTENTIALS DURING HYPOXIA AS COMPARED WITH PROPRANOLOL, DILTIAZEM AND GLIBENCLAMIDE IN GUINEA-PIG VENTRICULAR MUSCLE

The inhibitory effect of beraprost on the transmembrane action potenti als was compared with other cardioprotective drugs during hypoxia in g uinea-pig isolated right ventricular muscle. Glibenclamide, like berap rost, inhibited the decrease of the action potential duration, but pro panolol and diltiazem did not affect this decrease during hypoxia. In beraprost-treated preparations, the decrease of the myocardial K+ cont ent during hypoxia was inhibited. Furthermore, beraprost prevented the action potential shortening during metabolic inhibition by 2,4-dinitr ophenol. It is suggested that beraprost may inhibit the hypoxia- and 2 ,4-dinitrophenol-induced shortening of the action potential duration b y preserving the muscular ATP level. Accordingly, beraprost may have b eneficial effects both during hypoxia and metabolic inhibition.