Effects of beta-adrenoceptor antagonists on portal vein hypertension and ethanol-induced gastric mucosal damage in rats.

The effects of various beta-adrenoceptor antagonists, with different pharmacological properties, on systemic and portal vein blood pressure and on ethanol-induced gastric mucosal damage were examined in surgically-induced portal hypertensive rats. Propranolol (5, 10 or 20 mg kg-1), nadolol (5 or 10 mg kg-1), metoprolol (10 or 20 mg kg-1), labetalol (20 or 40 mg kg-1) and pindolol (3 or 6 mg kg-1) reduced systemic blood pressure to a similar degree in both portal vein-ligated and sham-operated rats. All beta-adrenoceptor antagonists, except for pindolol, significantly reduced portal venous pressure and ethanol-induced macroscopic gastric mucosal damage in portal hypertensive animals. Sham-operated rats had lower portal venous pressure and less gastric damage compared with portal hypertensive rats, but both were unaffected by beta-adrenoceptor antagonist pretreatment. We conclude that: propranolol, nadolol, metoprolol and labetalol are effective in reducing the portal venous pressure and ethanol-induced gastric mucosal damage in portal hypertensive rats, but not in portal normotensive animals; there was no direct relationship between the reduction of portal vein and systemic blood pressure; and local anaesthetic action is probably important in reducing the portal vein pressure and ethanol-induced gastric mucosal lesions, while the intrinsic sympathomimetic effect can counteract the actions of the beta-adrenoceptor antagonists on portal venous pressure and gastric mucosa.