Cerebral circulatory and metabolic effects of vasoactive intestinal polypeptide

Abstract

Two aspects of the action of vasoactive intestinal polypeptide (VIP) within the cerebral vascular bed were examined. In anesthetized cats, the vasomotor responses of individual pial arterioles on the convexity of cerebral cortex to perivascular VIP microinjection were examined and, in anesthetized baboons, the effects of VIP on cerebral blood flow, cerebral O2 consumption and EEG were investigated both prior to and following the osmotic opening of the blood-brain barrier. Perivascular VIP microinjection resulted in statistically significant increase in arteriolar caliber in the concentration range 10-9-10-6 M. Arteriolar caliber was increased by 22 .+-. 3% (mean .+-. SE) following VIP injection (10-8 M). In the 2nd series, in baboons, intracarotid VIP infusion (10-11 mol/min) did not affect cerebral blood flow, cerebral O2 consumption or the EEG under normal circumstances. If the same VIP concentration was administered following hypertonic opening of the blood-brain barrier, cerebral blood flow and O2 consumption were both elevated (by 37 .+-. 7% and 28 .+-. 10%, respectively), accompanied by increased EEG activity.