Topical effects of 16,16-dimethyl prostaglandin E2 on gastric blood flow in dogs.

The effects of luminal instillation of 16,16-dimethyl prostaglandin E2 (dmPGE2) on total gastric blood flow and its fractional distribution between the layers of gastric tissue were determined in exteriorized segments of the greater curvature of dog stomach. Total gastric blood flow was measured simultaneously by venous outflow and alpha-labeled microspheres; both methods correlated well with each other (r = 0.88, P less than 0.01). In the nonstimulated stomach, dmPGE2 caused an increase in total gastric blood flow from 4.2 +/- 0.8 to 7.4 +/- 1.2 ml/min (P less than 0.05). In contrast, dmPGE2 significantly reduced gastric blood flow in histamine-stimulated stomach (from 14.6 +/- 1.2 to 9.2 +/- 1.0 ml/min; P less than 0.01). The changes in mucosal blood flow ere proportional to the alterations in total blood flow because the fractional distribution of blood flow to the mucosa remained relatively unchanged during dmPGE2 administration. These observations suggest that dmPGE2, a known vasodilator, induces an increase in gastric blood flow in the resting stomach, whereas it reduces gastric blood flow in the actively secreting stomach as a result of secretory inhibition.