Effects of Bay K 8644 on the spontaneous electrical and mechanical activities of the rat portal vein.

Effects of Bay K 8644 on the spontaneous electrical and mechanical activities of the rat portal vein were studied. Bay K 8644 enhanced contractions in amplitude and duration. Bay K 8644 prolonged the duration of the spontaneous spike potential bursts and increased the number of spike potentials in a burst. These results indicate that the increase in the amplitude and duration of spontaneous contractions of the rat portal vein induced by Bay K 8644 are mediated mainly by the facilitation of the membrane electrical activity.