Effects of histamine, vasopressin, and angiotensin II on hepatosplanchnic hemodynamics, liver function, and hepatic metabolism in cats.

Abstract

Continuous i.v. infusions of histamine (5 mug/kg - min), vasopressin (10 mU/kg -min), or angiotensin II (0.5 mug/kg - min) were given to fasting cats. Hepatic arterial flow was decreased 30% by histamine, increased 30% by vasopressin, and not significantly affected by angiotensin, whereas portal venous flow was increased 25% by histamine, decreased 40% by vasopressin, and not significantly affected by angiotensin. The hepatic arterial conductance was decreased about 25% by histamine and angiotensin, and not significantly affected by vasopressin. The gastrointestinal conductance was decreased about 40% by vasopressin and angiotensin, and increased 25% by histamine. The conductance in the intrahepatic low pressure vessels was not affected by histamine and vasopressin, but decreased 25% during the infusion of angiotensin. These hemodynamic effects, however, were not accompanied by changes in the liver function or hepatic metabolism as judged from the splanchnic elimination of ethanol, the hepatic uptake and excretion of ICG, the hepatic oxygen consumption, and lactate and ketone production. This indicates that the functional capacity of the liver and thereby the number of sinusoids perfused is not markedly influenced by these drugs. Vasopressin caused a decrease in the oxygen consumption and an increase in the lactate production in the prehepatic splanchnic area, which may be due to a redistribution of the gastrointestinal blood flow.