AJP - Heart and Circulatory Physiology, Vol 257, Issue 4 1254-H1262, Copyright © 1989 by American Physiological Society
Coronary hemodynamic effects of intravenous vasoactive intestinal peptide in humans
T. C. Smitherman, J. J. Popma, S. I. Said, G. J. Krejs and G. J. Dehmer
Medical Services, Veterans Administration Medical Center, Dallas 75216.
Vasoactive intestinal polypeptide (VIP), a probable neurotransmitter, is
present in the hearts of experimental animals and is a coronary vasodilator
in dogs. We evaluated the coronary hemodynamic effects of intravenously
infused VIP in 11 men at two rates that modestly raised circulating VIP
concentrations. The decreases in coronary and systemic vascular resistances
during the second infusion, 33 and 31%, respectively, were slightly but
insignificantly greater than the 24% decrease in pulmonary vascular
resistance. Coronary sinus levels of 6-keto-prostaglandin F1 alpha were not
elevated during the infusions, and cyclooxygenase inhibition did not
significantly blunt coronary vasodilation. However, myocardial oxygen
uptake rose significantly during both infusions. To test for a direct
coronary vasodilator effect, we infused VIP into the left coronary artery
of four other men at four levels. The maximum decline in coronary vascular
resistance was 46% and was not associated with an increase in myocardial
oxygen uptake. We conclude that 1) intravenous administration of low to
intermediate doses of VIP in humans is associated with substantial coronary
vasodilation, 2) the coronary bed appears to be at least as responsive as
other vascular beds, 3) the coronary vasodilation is due to both direct and
indirect effects, and 4) the coronary vasodilation does not appear to be
mediated by prostaglandins.
