Effects of beraprost on the transmembrane potentials of guinea‐pig ventricular muscles during normoxia and hypoxia‐reoxygenation

Abstract

1 The present study was performed to determine whether beraprost, a new stable analogue of prostacyclin, may exert beneficial effects on the transmembrane action potentials during normoxia and hypoxia-reoxygenation in isolated right ventricular muscles of the guinea-pig.2 Under normal oxygenation, beraprost (0.01-100 imol'1) had no effects on the electrophysiological parameters. 3 Hypoxic conditions induced a decrease in action potential duration (APD) without affecting other action potential parameters. Beraprost inhibited this hypoxia-induced decrease in APD. However, beraprost had no effect on the decrease in contractile force induced by hypoxia, whereas it significantly improved the recovery of contractile force after reoxygenation. 4 Pinacidil-induced shortening of APD was not antagonized by beraprost. 5 Hypoxia significantly decreased the myocardial adenosine triphosphate (ATP) level, which was also prevented by beraprost. 6 These results suggested that beraprost may inhibit the hypoxia-induced shortening of APD by some mechanisms which contribute to the maintenance of muscle ATP level.