Effects of prostaglandins and indomethacin on gastric emptying in the rat.

Prostaglandins have been shown to stimulate contraction of gastrointestinal smooth muscle in vitro, and their synthesis has been reported in different gastrointestinal diseases. The aim of this study was to determine the different effects of PGs and indomethacin on gastric emptying in the rat in vivo, and to investigate their possible role as modulators of osmolarity induced changes in gastric emptying. Rats were fed via gastric tube with suspensions of various osmolarity containing different prostaglandins or indomethacin. Gastric emptying, measured by the quantity of food remaining in the stomach, was studied by a noninvasive technique using orally administered nonabsorbable marker 141Cerium. PGE2 given orally and its synthetic analogue 16-16-dimethyl PGE2 given subcutaneously caused significant delay of gastric emptying, while PGF2 alpha increased gastric emptying regardless of the administration route. Tube-feeding with high osmolarity suspension significantly reduced emptying rate of 141Cerium compared to feeding with low osmolarity suspension. Gastric emptying rate of the tracer was significantly higher in rats fed with low osmolarity test meal, in comparison to those fed with high osmolarity test meal. This effect was completely antagonized by indomethacin. Due to the known inhibitory effect of indomethacin on cyclooxygenase, the effects observed in the present study are also presumably mediated by the action of prostaglandins.