Influence of primary prostaglandins, prostacyclin and arachidonic acid on mesenteric hemodynamics in the pig.

In anesthetized young pigs the influence of intraarterial infusion of prostaglandin E2, prostacyclin, prostaglandin F2 alpha, and arachidonic acid on mesenteric vascular resistance was studied. Infusion of PGE2 and prostacyclin induced a dose-dependent direct decrease in resistance. Infusion of PGF2 alpha resulted in a dose-dependent difference in response. Infusion of lower doses provoked a decrease in mesenteric vascular resistance, whereas infusion of higher doses resulted in an increase. Lower doses of arachidonic acid induced a gradual decrease in resistance, while higher doses provoked biphasic or triphasic responses. After previous blockade of the PG synthetase and lipoxygenase pathways with indomethacin and ETA, arachidonic acid only provoked a decrease in vascular resistance. The resultssuggest a possible role of prostaglandins and their precursors in autoregulation of mesenteric blood flow in the pig.