[The influence on heart conduction time and refractory period of in vitro and in vivo prostaglandins].

The effects of PGE1, PGE2 and PGF2alpha on conduction time and functional refractory period in the isolated rabbit atrium and in the cat heart in vivo were investigated. In the isolated rabbit atrium the PGs (10(-8)--10(-5) g/ml) were without any effect in this respect. In contrast there was a dose-dependent decrease of conduction time and prolongation of functional refractory period in the cat heart in vivo following PG-infusions (2,0--8,0 mug/kg/min i.v. over a period of 5 min). These findings indicate the absence of a direct quinidine-like membrane action of PGs in the heart. The indirect, depressive effects of PGs on conduction time and functional refractory period in the heart in vivo, should be considered responsible for the antiarrhythmic action of PGs.