Mast cell mediators excite the afferents of cat small intestine

The influence of intra-arterial injections of 5-hydroxytryptamine, histamine and prostaglandin E(2) on afferent impulse activity of mesenteric nerves of small intestine was studied. In anaesthetized cats 5-hydroxytryptamine (10(-8)-10(-4) M) and histamine (10(-8)-10(-3) M) were shown to increase the impulse activity in a dose-dependent manner. Metergolin, 5-hydroxytryptamine antagonist, suppressed the effect of 5-hydroxytryptamine. Clemastine and cimetidine, antagonists of H-1 and H-2 histamine receptors respectively, distinctly diminished excitatory histamine effects. Prostaglandin E(2) (10-30 mu g/kg) enhanced the afferent impulse activity. The results suggest that afferents of the small intestine may be involved in reception of inflammatory and immune responses.