Effects of intra-arterially infused adenosine triphosphate (ATP) on release of vasoactive intestinal polypeptide (VIP) from the gastrointestinal tract of the cat.

Close i.a. infusions of ATP were made to the stomach, the small intestine or the colon in the cat. The vascular reactions were followed by recording arterial pressure and total venous outflow continuously and the release of VIP was estimated intermittently from arterio-venous concentration differences and blood flow. In all experiments ATP caused a vasodilatation and an increased release of VIP into blood. In control experiments it was shown that evoking a vasodilatation of the same magnitude by close i.a. infusions of isoprenaline or papaverine did not evoke any similar release of VIP. It is concluded that the infused ATP released VIP from the different parts of the gastrointestinal tract. Possible mechanisms underlying this effect are tentatively discussed.