title: The effect of intravenous PACAP38 on cerebral hemodynamics in healthy volunteers.
abstract: PACAP38 is an endogenous peptide located in trigeminal perivascular nerve fibers in the brain. It reduces neuronal loss and infarct size in animal stroke models and has been proposed a candidate substance for human clinical studies of stroke. The effect on systemic hemodynamics and regional cerebral blood flow (rCBF) is not well understood. We here present the first study of the effect of PACAP38 on cerebral hemodynamics in humans. PACAP (10 pmol kg(-1) min(-1)) or placebo (0.9% saline) was infused for 20 min into 12 healthy young volunteers in a cross over, double blind study. rCBF was measured with SPECT and (133)Xe inhalation and mean blood flow velocity in the middle cerebral artery was measured with transcranial Doppler ultrasonography. End tidal partial pressure of CO(2) (P(et)CO(2)) and vital parameters were recorded throughout the 2 hour study period. PACAP38 decreased rCBF in all regions of interest (ROIs) by approximately 3-10%, though not uniformly significant. P(et)CO(2) decreased significantly during PACAP38 infusion compared to placebo (P=0.032), peak decrease was 8.9+/-3.8%. After correction for P(et)CO(2), rCBF remained unchanged in most ROIs. Heart rate increased 61.9+/-22.4% (P<0.0001 vs. placebo). These findings suggest that PACAP38 has no major direct effect on rCBF in healthy volunteers. The marked increase in heart rate and the reduction in rCBF caused by decreased P(et)CO(2) are important dose-limiting factors to consider in future clinical studies.
authors.affiliation: Danish Headache Center, Department of Neurology, Glostrup Hospital, University of Copenhagen, Denmark. birk@dadlnet.dk
authors.forename: Steffen
authors.initials: S
authors.lastname: Birk
authors.forename: John Thomas
authors.initials: JT
authors.lastname: Sitarz
authors.forename: Kenneth Ahrend
authors.initials: KA
authors.lastname: Petersen
authors.forename: Peter Sandor
authors.initials: PS
authors.lastname: Oturai
authors.forename: Christina
authors.initials: C
authors.lastname: Kruuse
authors.forename: Jan
authors.initials: J
authors.lastname: Fahrenkrug
authors.forename: Jes
authors.initials: J
authors.lastname: Olesen
mesh_terms: D000293:Adolescent; D000328:Adult; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000097:blood / Q000494:pharmacology*; D012016:Reference Values; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014665:Vasodilator Agents