Chronic portal hypotensive effects of tetrandrine and verapamil on portal hypertensive rats

Tetrandrine is a calcium channel antagonist with reported anti-hypertensive effect. However, the potential role of tetrandrine as a therapeutic agent in portal hypertension has yet to be explored. The present study aimed To investigate the chronic effects of two calcium channel antagonists, tetrandrine and verapamil, on the portal pressure of portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Animals were allocated into one of the two groups: tetrandrine group and verapamil group. Tetrandrine group was sub-divided into 10, 30, 50 mg/kg and vehicle (0.1 N HCl) subgroups. Verapamil group was sub-divided into 10, 30, 50 mg/kg and vehicle (saline) subgroups. Drug or vehicle was administered by gavage every 12 hours for 9 consecutive days, starting 2 days before ligation and continuing thereafter. After 9 days of tetrandrine treatment, portal venous pressure was significantly reduced in the subgroups receiving 30 and 50 mg/kg (12.6 +/- 0.3 mmHg, p < 0.05 and 9.7 +/- 0.6 mmHg, p < 0.01 vs. vehicle, respectively) as compared to vehicle group (14.1 +/- 0.6 mmHg). Mean arterial pressure was reduced only in the subgroup receiving the highest dose. There was no difference in body weight or heart rate between the vehicle and any tetrandrine subgroup. After 9 days of verapamil treatment, portal venous pressure was significantly reduced in the subgroups receiving 30 and 50 mg/kg (12.1 +/- 0.5 mmHg, p < 0.05 and 11.9 +/- 0.6 mmHg, p < 0.01 vs. vehicle, respectively) as compared to vehicle group (14.2 +/- 0.4 mmHg). Mean arterial pressure and heart rate were reduced only in the subgroup receiving the highest dose. There was no difference in body weight between the vehicle and any verapamil subgroup. Our results showed that chronic treatment of tetrandrine or verapamil reduced portal Venous pressure in portal hypertensive rats.