Effect of verapamil on renal haemodynamics in a portal hypertensive rat model

In order to investigate the effects of verapamil on renal haemodynamics in rats with portal hypertension, verapamil was given at either a low (0.2 mg/kg) or high (2 mg/kg) dose to rats after portal vein ligation. An approximate 12% decrease in mean arterial pressure followed administration of low dose verapamil, with a significant decrease in cardiac output and renal blood flow, as well as reduced portal pressure, observed; these signs were all indicative of a rise in renal vascular resistance. In contrast, the marked fall in both mean arterial pressure and cardiac output with high dose verapamil, accompanied by a significant decrease in portal pressure and no change in renal blood flow, suggests a reduction in renal vascular resistance. This study shows that the acute effects of verapamil on renal haemodynamics may vary with the dose used. Also, acute verapamil administration tends to decrease renal blood flow to alter the autoregulation of the kidney; thus, caution should be taken in the clinical use of verapamil in the treatment of cirrhosis with portal hypertension.