Effects of prostaglandin E2 and indomethacin on responses of the isthmus of rabbit oviduct to norepinephrine and transmural stimulation.

The effects of prostaglandin E2 and of indomethacin on the responses of the circular muscle of the isthmus of rabbit oviduct to (-)-norepinephrine and to transmural stimulation were determined. At 26 degrees C, 10 ng/ml prostaglandin E2 significantly reduced responses to transmural stimulation but had little effect on responses to (-)-norepinephrine. At 26 degrees C, 5.6 x 10(-5)M indomethacin slightly reduced responses to both transmural stimulation and to (-)-norepinephrine. At 37 degrees C, spontaneous desensitization to both stimulation and to (-)-norepinephrine occurred but transmural stimulation was more inhibited. Addition of 2.8 x 10(-6)M indomethacin prevented this desensitization. These results suggest that responses of the isthmus of rabbit oviduct to (-)-norepinephrine were not dependent on prostaglandin generation. Adrenergic transmission to the oviduct was, however, inhibited by prostaglandin E2. Evidence was also obtained for the spontaneous liberation at 37 degrees C of prostaglandins that inhibited the contractility of the oviduct.