1. The effects of propranolol on heart rate, arterial pressure, portal venous pressure and fractional hepatic blood flow were studied in rats with hepatic artery ligature or with portal vein stenosis, and in sham-operated rats. The effect of propranolol on cardiac output was also studied in normal rats.
2. In rats with hepatic artery ligature or with portal vein stenosis, and in sham-operated rats, propranolol decreased heart rate and portal venous pressure significantly and did not alter arterial pressure. Propranolol decreased fractional hepatic blood flow significantly in rats with hepatic artery ligature, but did not change hepatic blood flow in rats with portal vein stenosis or in sham-operated rats.
3. We conclude therefore that: (a) propranolol decreases portal venous pressure in rats; (b) this decrease in portal venous pressure results in a reduction in portal blood flow which is related, in part, to a reduction in cardiac output; (c) propranolol does not alter hepatic blood flow in normal rats or in rats with portal hypertension.