In vivo effects of prostaglandin F2 alpha and E2 on contractility and diameter of the rabbit oviduct using intraluminal transducers.

Abstract

Donut-shaped conductive Silastic micro-transducers were used to study the effects of intravenous administration of prostaglandin (PG) F2a and E2 on contractility and internal diameter of the oviductal isthmus in unanesthetized rabbits. The characteristic response to PGF2 a was an abrupt increase in internal diameter and a concomitant increase in frequency of contractions. In a few animals there was either no change in baseline diameter or only a gradual decrease in diameter. In all animals responding to PGF2 a there was a consistent increase in frequency of contractions, but normally little increase in amplitude of contractions. Simultaneous cinematographic recordings during acute experiments indicated that abrupt increases in internal diameter were associated with contraction of longitudinal muscles and/or mesentery. The effect of epinephrine was similar to that of PGF2 a. Prostaglandin E2 blocked spontaneous activity of the longitudinal and circular muscles but produced little change in internal diameter. Response to PGE2 was similar to that observed for isoproterenol. Measurement of contractility and internal diameter suggests that PGF2 a increases the rate of egg transport by increasing oviductal diameter as well as increasing the rate of contractions. No change in diameter and blockage of spontaneous activity could explain why PGE2 has little effect on egg transport rates.