The activity of non-steroidal anti-inflammatory drugs in the rat mesenteric vasculature.

Abstract

Rat isolated, perfused mesenteric blood vessels have been used to determine whether non-steroidal anti-inflammatory drugs (NSAIDs) display selectivity for inhibition of vasoconstrictor responses to noradrenaline compared with those to calcium. The rank order of potency of the NSAIDs for inhibition of responses to noradrenaline was: meclofenamate greater than flufenamate = diclofenac greater than indomethacin greater than fenbufen greater than phenylbutazone greater than ibuprofen greater than ketoprofen greater than naproxen greater than paracetamol (included as an inhibitor of cyclo-oxygenase). All NSAIDs show selectivity for noradrenaline (mean selectivity molar ratio = 0.19; s.e.m. 0.15-0.23) but there was a positive correlation (r = 0.98, P less than 0.001) between inhibition of responses to noradrenaline and those to calcium. The depressant effect of meclofenamate and of fenbufen, the most potent and most selective in the series, respectively, on responses to noradrenaline, was completely reversed to control values by prostaglandin E2. The results support previous findings that inhibition of cyclo-oxygenase in rat mesenteric blood vessels leads to a loss of response to noradrenaline. Comparison of the present data for inhibition of responses to noradrenaline in the mesentery with published data indicates that the mesentery bears a greater similarity to other in-vitro rather than in-vivo models for screening NSAIDs.