The microvasculature of the small-intestinal mucosa of the rat: quantification of hemodynamic effects of topically applied cimetidine, ranitidine, somatostatin, and vasopressin.

The influence of topically administered cimetidine, ranitidine, somatostatin, and vasopressin on microvessels of the jejunal villus of the rat was investigated by means of an in vivo videomicroscopy technique. For all substances a dose-response curve concerning the change of vessel diameters was obtained. All four drugs induced a significant vasoconstriction at the capillary level. Maximum vasoconstriction was achieved with vasopressin. These results strongly suggest the presence and possibly importance of H2 receptors in the intestinal vascular bed of the rat.