Spontaneous motility and prostaglandin generation in rat uterine horns isolated during the estrous cycle.

Measurements were made of spontaneous contractions and release of prostaglandin E-and F-like material into the bathing medium by uterine horns isolated from rats in different stages of the sex cycle. After 70 min of contractile activity the preparations from estrous rats released more PGF than those from proestrous or metestrous rats. On the other hand, similar amounts of PGF-like material is generated by estrous and diestrous horns. Less PGE-like material was found in the bathing solution during estrus than in metestrus or diestrus; the values obtained during proestrus were similar to those in estrus. PGI2 like material produced by chopped uterine tissue was greater during diestrus than in estrus. The initial isometric developed tension (IDI) and tension constancy varied depending of the stage of the sex cycle. Uteri from metestrous rats exhibited greater IDT and less % change with time than preparations from estrous or proestrous rats. The initial IDT, the tension change with time and contractile frequency correlate with the PGE-like material in the bathing solution during the 4 days of the sex cycle. There was no correlation with PGF-like material.