AN EVALUATION OF WHETHER DURATION OF PERFUSION ALTERS VASCULAR-RESPONSES IN THE ISOLATED DUAL-PERFUSED RABBIT LIVER

The isolated dual-perfused rabbit liver has been used to characterize hepatic arteriaI vascular receptors. These hepatic arterial responses are reproducible for 2.5 hr. Further studies in relation to the assessment of portal venous responses using this model require longer periods of perfusion. This study was designed to determine if this model is suitable for the assessment of hepatic arterial and portal venous vascular responses over a 5-hr perfusion period. Hepatic arterial responses were consistent to all agents during 5 hr of perfusion. Portal venous responses to the direct smooth muscle acting agents, sodium nitroprusside and adenosine, were constant, but the vasoconstrictor responses to acetylcholine and adenosine 5'-triphosphate (agents that cause an endothelium-independent vasoconstriction and an endothelium-dependent vasodilatation) were potentiated. Coarse measurements of liver function were also performed and suggested that the liver remained viable for the 5 hr of perfusion. These results suggest a decrease in the ability of the endothelium of the portal venous vasculature to respond to vasoactive substances as duration of perfusion increases. The possible reasons for this are discussed.