AJP - Gastrointestinal and Liver Physiology, Vol 239, Issue 5 378-G381, Copyright © 1980 by American Physiological Society
Hepatic artery response to vasopressin
T. E. Bynum and J. W. Fara
As vasopressin began to be used widely to control gastrointestinal
hemorrhage, there was concern over the effect of vasopressin on the hepatic
circulation. Although an initial vasoconstrictor effect of the drug has
been described on the hepatic artery, a secondary increase in blood flow
ensues. This increase has been attributed to the accompanying decrease in
portal blood flow produced by vasopressin. The present study was done to
investigate the mechanism of the response of hepatic artery to vasopressin
in dogs. Anesthetized dogs were studied with flow probes placed on hepatic,
superior mesenteric, femoral, and renal arteries, and the animals were
prepared so that portal blood was diverted into jugular vein, with portal
inflow to liver delivered at varying rates with blood pumped from a femoral
artery. Vasopressin (0.5-1.0 U/kg) was administered intravenously. Results
in dog indicate the biphasic response of hepatic artery blood flow to
vasopressin is not dependent on changes in portal blood flow. Rather, it
appears to be a characteristic response of this vessel. The biphasic
response was not observed in other vascular beds studied and was not
modified by atropine. beta-Adrenergic blockade enhanced the vasoconstrictor
portion of the response, but this did not significantly alter the secondary
blood flow increase.
