The effect of vasopressin and hepatic artery ligation on the blood supply to normal and metastatic liver tissue.

The effect of low (0.08 microU g-1 body wt min-1) and high (0.16 microU g-1 body wt min-1) rates of vasopressin infusion on blood flow to normal liver tissue and to liver metastases derived from azoxymethane induced colorectal carcinomas was studied in 36 male Wistar rats. Portal venous flow was measured by electromagnetic flowmetry and blood flow to normal and metastatic liver tissue by the clearance of xenon-133 injected directly into the liver parenchyma or metastasis. The low rate of vasopressin infusion decreased portal venous flow but increased blood flow to normal and metastatic liver tissue while at the higher rate of infusion these effects were reversed. Hepatic artery ligation (HAL) immediately following a low rate of vasopressin infusion abolished the observed increase in blood flow to both normal liver tissue and metastases. HAL immediately following the higher rate of vasopressin infusion further reduced blood flow to metastases but did not further alter blood flow to normal liver tissue. HAL prior to the infusion of the vasoactive drug significantly reduced blood flow to metastatic liver tissue, increased portal venous flow and was without effect on blood flow to normal liver tissue. Following HAL, blood flow to metastatic liver tissue was not further altered by either the low or high rates of vasopressin infusion. However, blood flow to normal liver tissue after HAL was reduced by a low rate of infusion of vasopressin and increased by the higher rate of infusion. The results of this study indicate that blood flow to normal or metastatic liver tissue can be increased or decreased by differential rates of infusion of vasopressin. These observations may have important implications in the treatment of liver metastases in man where different rates of vasopressin infusion may potentiate the effects of hepatic artery ligation or cytotoxic therapy.