Ovine ureteral motility as a new assay for the cyclo-oxygenase blocking potency of non steroidal anti-inflammatory drugs.

Isolated sheep ureteral ring suspended in an organ bath exhibits rhythmic contractions which are dose-dependently inhibited by indomethacin and revived by prostaglandin E2 or F2 alpha. Seven non-steroidal anti-inflammatory drugs (NSAID) belonging to different chemical groups were tested on the isolated ureteral ring model in molar concentrations of 10(-8)-10(-4) to determine the time elapsing from application of test drug to complete inhibition of ureteral contraction ("stop-time"). The descending order of potency of the NSAID was: flurbiprofen greater than indomethacin greater than flufenamic acid greater than tolmetin greater than aspirin greater than phenylbutazone greater than isoxicam. A parallelism was observed in the plot of log concentration of NSAID and "stop-time" amongst all compounds except aspirin and isoxicam. The sheep isolated ring preparation is a simple reproducible biological model for assessment of anti-inflammatory cyclo-oxygenase inhibitory activity of compounds.