Analysis of the contractile responses of the ileal segment of the isolated blood-perfused small intestine of rats to adenosine triphosphate and related compounds.

For close-arterial injection the isolated small intestine of the rat was perfused by a cross-circulation technique at a fixed flow rate through the superior mesenteric artery with arterial blood from a donor. Single intra-arterial injections of purine derivatives elicited a monophasic fast contraction of the ileum. In order to elucidate the mechanism of the fast contraction, adenosine triphosphate (ATP) was chosen for further investigations. The ileal response to ATP was abolished by tetrodotoxin, hexamethonium or morphine, but was resistant to blockade by atropine, methysergide or mepyramine. These results definitely indicate that ATP causes the fast contraction of the ileum by a stimulation of neuronal elements in the myenteric plexus involving cholinergic interneurons.