Clinical Investigation and Reports Diminished Vascular Response to Inhibition of Endothelium-Derived Nitric Oxide and Enhanced Vasoconstriction to Exogenously Administered Endothelin-1 in Clinically Healthy Smokers

Background Smoking is a major risk factor for the devel-opment of atherosclerosis. Because endothelial dysfunction may be a marker for future atherosclerosis, we investigated the effects of smoking on endothelium-dependent control of vas-cular tone. Methods and Results The effects of brachial arterial infu-sions of N0-monomethyl-L-arginine (L-NMMA), a nitric oxide synthesis inhibitor; sodium nitroprusside; endothelin-1; and norepinephrine on forearm blood flow (strain-gauge plethys-mography) were compared in 29 long-term smokers and 16 nonsmokers. The acute effects of smoking on systemic hemo-dynamics, plasma catecholamines, and forearm vascular re-sponses to these compounds were investigated in smokers only. Smokers did not differ from nonsmokers (n = 16) regard-ing the vascular effects of sodium nitroprusside (n = 13) o