Ionic composition of small intestinal secretion induced by PGE2.

Small intestinal fluid secretion induced by oral prostaglandin E2 in fasted rats was analyzed for various ionic components. Rat intestinal fluid had elevated calcium and potassium as well as decreased sodium and chloride concentrations relative to plasma electrolytes. Either low dose prostaglandin (0.15 mg/kg) or 1 ml of intragastric mannitol (5%) induced accumulation in the small intestine of fluid that had elevated chloride and depressed calcium and sodium concentrations compared to vehicle-treated controls. Higher doses of prostaglandin (1.0 mg/kg) led to secretions with increased sodium and chloride concentrations with respect to mannitol-induced fluid. Electrolyte concentrations in fluid induced by low dose prostaglandin appear to be similar to those in fluid caused by osmotically-induced changes. Higher doses of prostaglandin E2 induce additional electrolyte alterations which may result from modified gut transport of water and ions.