ACUTE EFFECTS OF SUBLINGUAL NITROGLYCERIN ON HEPATIC BLOOD-FLOW IN HEALTHY-VOLUNTEERS

Duplex sonography was used to assess the effects on hepatic blood flow after administering 0.6 mg nitroglycerin (NTG) sublingually to ten he althy volunteers. The study was a randomized, placebo-controlled, cros s-over study in which subjects were studied on three separate occasion s. Each visit involved administering either placebo or NTG followed by estimation of blood flow through a particular branch of the hepatic a rtery, portal vein, and hepatic vein every minute for is minutes after NTG and placebo administration, Two hours later, subjects were crosse d over to the other treatment and the same vessel branch was again exa mined for 15 minutes. Total blood flow increased 7% in the portal vein and 27% in the hepatic vein during NTG treatment, but did not change significantly in the hepatic artery. Vascular resistance was increased in the hepatic artery and decreased in the portal and hepatic veins a fter NTG. Qualitatively, flow changed dramatically in the hepatic vein after NTG with the disappearance of normal retrograde flow. The resul ts indicate that nitroglycerin effects hepatic blood flow through the portal and hepatic veins with a decrease in vascular resistance in the portal and hepatic veins and an increase in resistance in the hepatic artery.