Effects of Somatostatin on Hepatic Haemodynamics in the Cirrhotic Rat

Abstract

Reports on the effects of somatostatin on hepatic haemodynamics in the cirrhotic patient have provided conflicting results. Therefore, we studied the effects of different modes and rates of somatostatin administration on hepatic haemodynamcis in the cirrhotic rat. Portal pressure (PP), wedged hepatic venous pressure (WHVP), portal venous flow (PVF), liver blood flow (LBF) and systemic blood pressure were measured in rats with dimethylnitrosamine-induced cirrhosis. Somatostatin was administered as a rapid injection, a continuous infusion or as a bolus dose followed by a constant infusion. One group of rats with a previously constructed portacaval shunt received a bolus dose of somatostatin followed by a constant infusion. A rapid injection of somatostatin was attended by a rapid and significant fall in all the haemodynamic parameters measured (p < 0.01). Continuous infusion of somatostatin [4 or 8 μg/kg body weight (BW) h] resulted in a gradual but significant reduction in PP, WHVP, PVF and LBF (p < 0.05), but had no effect on systemic blood pressure. A bolus dose of somatostatin (2, 4 or 8 μg/kg BW over 2 min) resulted in a rapid decrease in PP, WHVP, PVF and LBF (p < 0.01), the decreases being maintained by continuous infusion. In rats with a portacaval shunt a bolus dose of somatostatin (8 μg/kg BW) resulted in a rapid fall in WHVP and LBF, the decrease being maintained by a continuous infusion (8 μg/kg BW/h). We conclude that in the cirrhotic rat, (1) a bolus dose of somatostatin followed by a continuous infusion is more effective than a continuous infusion in producing and maintaining a significant reduction in PP, WHVP, PVF and LBF; (2) somatostatin has little effect on systemic blood pressure unless it is administered very rapidly; (3) previous conflicting reports on the effects of somatostatin on hepatic haemodynamics in the cirrhotic patient may be related to the rate or mode of administration of the hormone.