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

Abstract

To elucidate the effects of verapamil on splanchnic haemodynamics in rats with portal hypertension, verapamil was given at a low dose (0.2 mg/kg) and a high dose (2 mg/kg) to the rat model after portal vein ligation. Approximately 10% decrease in arterial pressure was caused by the low dose of verapamil, with significant decreases in cardiac output and portal venous inflow as well as reduced portal pressure; these were all indicative of a rise in portal vascular resistance. In contrast, the marked fall in both arterial pressure and cardiac output in the high dose, accompanied by a significant decrease in the portal pressure and the unchanged portal venous inflow, suggested a reduction in portal vascular resistance. This study shows that the acute effects of verapamil on portal hypertension may vary with the dosage used. These results also demonstrate that, since the therapeutic efficacy and safety of verapamil is only in a very limited range of dose, caution should be taken in its clinical use in the treatment of cirrhosis with portal hypertension.

Hemodynamic Effects of Chronic Tetrandrine and Propranolol Administration on Portal Hypertensive Rats

“…As verapamil effects in portal hypertension are better documented, and little is known about tetrandrine, we, therefore, undertook the present study on tetrandrine. Although verap amil has been shown in some reports to reduce portal pressure and/or improve hepat ic function in both portal hypertensive pa tients [23] and animals [13,14,24], another calcium antagonist, nifedipine, has been shown to deleteriously increase hepatic ve nous pressure in cirrhotic patients [25]. In our acute [9] and in the chronic (the present) study of tetrandrine, we observed that portal venous pressure, mean arterial pressure, and total peripheral resistance were reduced in portal hypertensive rats, in line with previous reports of verapamil effects [3,24], It awaits further study to clarify whether tetrandrine alone has any deleterious side effects on renal, hepatic, or metabolic functions.…”