The net fluid secretion caused by cyclic 3'5‘‐guanosine monophosphate in the rat jejunum in vivo is mediated by a local nervous reflex

Abstract

The tissue concentration of cyclic 3'5'-guanosine monophosphate (cGMP) has been shown to increase in the small intestine when net fluid secretion is evoked by the heat-stable enterotoxine of Escherichia coli. Lipophilic cGMP analogues are also known to elicit intestinal fluid secretion. It is therefore believed that an increase in intracellular cGMP concentration in enterocytes mediates this secretion. The present study reports that the fluid secretion, elicited by placing two different cGMP analogues, dibutyryl-cGMP and 8-Br-cGMP, in the intestinal lumen of anaesthetized rats in vivo, is significantly inhibited by atropine, hexamethonium and lidocaine. It is proposed that cGMP activates a reflex in the enteric nervous system which, in part, explains the observed fluid secretion.