Effect of pituitary adenylate cyclase activating polypeptide 1-27 on ocular, cerebral and skin blood flow in humans

The aim of the study was to assess the effects of a neuropeptide, pituitary adenylate cyclase activating polypeptide 1-27 (PACAP), on ocular, cerebral and skin blood flow in man. PACAP (0.01-10 pmol kg(-1) min(-1)) was admini stered intravenously to eight healthy male subjects in a placebo-controlled , double-blind dose escalation trial. Fundus pulsation amplitude was measur ed by laser interferometry, mean blood flow velocity in the ophthalmic arte ry and the middle cerebral artery measured by Doppler sonography, and regio nal blood flow of the skin was estimated by laser Doppler flowmetry. Infusion of PACAP at the highest dose of 10 pmol kg(-1) min(-1) induced a s ignificant increase in fundus pulsation amplitude (+83.4%), mean flow veloc ity in the ophthalmic artery (+91.9%) and regional skin blood flow (+260.3% , P<0.01, ANOVA; each parameter). In contrast, PACAP did not cause any chan ge in middle cerebral artery blood flow velocity or systemic hemodynamics. Our findings indicate that the vasculatures of the eye and the skin are par ticularly sensitive to PACAP and may implicate a potential role for this pe ptide in the regulation of blood flow in these vascular beds.