RESUMEN
Little is known about the action adrenaline has on vascular areas of functionally different parts of the stomach and intestine. Therefore the vasoactivity of adrenaline (1-1024 ng/kg i.v.) was studied by electromagnetic flow measurements in 8 vascular beds covering the gastrointestinal tract. Adrenaline induced 1) a vasodilation in the lesser curvature and antrum of the stomach; 2) a vasoconstriction in the greater curvature of the stomach; 3) a vasoconstriction followed by a vasodilation in the duodenum and jejunum; 4) a vasoconstriction in the ileum, caecum/colon and colon/rectum. Phenoxybenzamine (750 micrograms/kg i.v.) blocked systematically the vasoconstriction in the duodenum and jejunum but not in the ileum and colon. Vasodilation could be blocked by propranolol (100 micrograms/kg i.v.). It is concluded that 1) adrenaline-effects are mediated predominantly by beta-receptors in the antrum and lesser curvature of the stomach; predominantly by alpha-receptors in the greater curvature of the stomach; by alpha- and beta-receptors in the duodenum and jejunum; 2) receptors in the large intestine are of another alpha-adrenergic type than those in the small intestines. Evidence was provided for a gradient of diminishing vasodilating effects of adrenaline from cranial to caudal of the gut.