The biphasic response of hepatic arterial blood flow caused by vasoactive substances--an experimental study in dogs

In ten male mongrel dogs, blood flow was measured in the common hepatic artery (CHA), portal vein (PV) and liver tissue before and after the injection of vasoactive substances: angiotensin II (1.0 micrograms/kg), prostaglandin F2 alpha (1.0 micrograms/kg) and vasopressin (0.1 Unit/kg), under observation of the systemic circulation. Each injection caused a biphasic response in CHA blood flow, an initial decrease followed by a marked increase, while PV blood flow decreased. Liver tissue blood flow was reduced just after injection, but soon returned to a normal level. The duration of action was the shortest with prostaglandin F2 alpha and the longest with vasopressin. In using vasoactive substances in pharmaco-angiography, it is important to consider the biphasic response in CHA blood flow as well as the duration of action of these substances.