The effect of indomethacin on the motility of isolated sheep ureters.

The possible spasmolytic effect of indomethacin was studied on isolated sheep ureteral preparations. Ureteral ring preparations suspended in an organ bath exhibited long lasting rhythmic contractions quite similar to the in vivo situation. This spontaneous motility was unaffected by hyoscine, phenoxybenzamine, propranolol, mepyramine and methysergide. Addition of indomethacin resulted in a dose dependent reduction in amplitude and frequency of the contractions, the threshold value being 10(-8) M. Washing reestablished motility and both PGE2 and PGF2 alpha were powerful stimulators of rhythmic contractions. Our conclusion is that in vitro rhythmic activity of the ureter is dependent on endogenous PG-synthesis and the cyclooxygenase inhibitor indomethacin dose-dependently blocks this.