EFFECTS OF PROSTAGLANDINS AND INDOMETHACIN ON GASTRIC-EMPTYING IN THERAT

Prostaglandins have been shown to stimulate contraction of gastrointes tinal smooth muscle in vitro, and their synthesis has been reported in different gastrointestinal diseases. The aim of this study was to det ermine the different effects of PGs and indomethacin on gastric emptyi ng in the rat in vivo, and to investigate their possible role as modul ators of osmolarity induced changes in gastric emptying. Rats were fed via gastric tube with suspensions of various osmolarity containing di fferent prostaglandins or indomethacin. Gastric emptying, measured by the quantity of food remaining in the stomach, was studied by a noninv asive technique using orally administered nonabsorbable marker Cerium- 141. PGE, given orally and its synthetic analogue 16-16-dimethyl PGE, given subcutaneously caused significant delay of gastric emptying, whi le PGF2alpha increased gastric emptying regardless of the administrati on route. Tube-feeding with high osmolarity suspension significantly r educed emptying rate of Cerium-141 compared to feeding with low osmola rity suspension. Gastric emptying rate of the tracer was significantly higher in rats fed with low osmolarity test meal, in comparison to th ose fed with high osmolarity test meal. This effect was completely ant agonized by indomethacin. Due to the known inhibitory effect of indome thacin on cyclooxygenase, the effects observed in the present study ar e also presumably mediated by the action of prostaglandins.