Methylxanthine induced small intestinal secretion

Methylxanthines, being potent phosphodiesterase inhibitors produce increased intestinal cyclic AMP levels and would be predicted to produce increased net intestinal fluid secretion. Their effect when presented to the intestinal lumen, which would be analogous to human ingestion, had not been previously determined. Isolated loops of rat jejunum were perfused with solutions of caffeine and theophylline in vivo. There was a decrease in net fluid absorption in both neonatal and mature animals exposed to theophylline. Mature animals exposed to caffeine developed a prompt secretory response, comparable to that induced by cholera toxin. The data indicate that methylxanthines are potent intestinal secretagogues when administered intraluminally and suggest that secretory stimulation could be important in the gastrointestinal symptomatology elicited in man by these compounds.