Effect of prostaglandin-E2 on myoelectrical and mechanical activity of totally isolated, ex-vivo-perfused, canine stomach.

Abstract

This study was concerned with the effects of prostaglandin-E2 (PGE2) on myoelectrical and mechanical activity of the isolated, homologous perfused canine stomach. A flash injection of 25 mug of PGE2 into the gastric artery led to production of premature control potentials, uncoupling of electrical control activity (ECA) and to a weak mechanical response of short duration. After vagal stimulation of the nerve of Latarjet, or after flash injection of pentagastrin (2.5 mug) or of methacholine (5 mug), similar changes in ECA were observed, but mechanical response corresponding to antral contractions was very pronounced. Prolonged infusion of PGE2 (500 mug/h) induced a marked increase of ECA frequency. A similar effect on ECA frequency was observed during infusion of pentagastrin (32 mug/h). Infusion of PGE2 abolished, but infusion of pentagastrin stimulated, mechanical response. Effects of a flash injection of PGE2 on electrical activity were reduced by hexamethonium and abolished by tetrodotoxin and atropine. The action of the blocking agents on PGE2-induced changes in ECA was similar to the action of these blockers on gastric myoelectrical activity, stimulated vagally or by injection of pentagastrin and methacholine. Infusion of PGE2 induced a marked reduction in gastric peripheral vascular resistance, but no time-correlation between hemodynamic effects of PGE2 and its action of gastric musculature was noted.