title: Vasoactivity of adrenaline in regions covering the canine gastrointestinal tract.
abstract: 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.
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003106:Colon / Q000098:blood supply; D004064:Digestive System / Q000098:blood supply*; D004285:Dogs; D004576:Electromyography; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007082:Ileum / Q000098:blood supply; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D007421:Intestine, Small / Q000098:blood supply; D008297:Male; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects
chemical_list: D010643:Phenoxybenzamine; D011433:Propranolol; D004837:Epinephrine