Short-term effects of smoking and nicotine chewing gum on endothelium-dependent vasodilation in young healthy habitual smokers.

Smoking is a major risk factor for coronary and peripheral vascular disease. This study was designed to investigate the short-term effects of smoking and nicotine gum on endothelium-dependent (EDV) and -independent (EIDV) vasodilation in the forearm of young habitual smokers. In 10 subjects, forearm blood flow (FBF) during local infusion of metacholine (4 microg/min, evaluating EDV) and sodium nitroprusside (10 microg/min, evaluating EIDV) was assessed before and at 10 min (early phase) and 30-50 min (plateau phase) after the initiation of smoking, using forearm venous occlusion plethysmography. Six subjects underwent similar measurements of FBF before and 30 min after chewing a nicotine gum (4 mg). As a change in blood pressure was expected, forearm vascular resistance (FVR) was used to calculate EDV and EIDV. FVR during metacholine infusion increased from 4.6 +/- 1.4 SD to 5.9 +/- 2.1 mm Hg/ml/min/100 ml tissue during the early and to 5.0 +/- 1.6 mm Hg/ml/min/100 ml tissue at the plateau phase of smoking (p < 0.01 for both vs. baseline) and from 4.5 +/- 1.6 to 5.2 +/- 1.6 mm Hg/ml/min/100 ml tissue after chewing the nicotine gum (p < 0.01). No significant changes in EIDV were seen after smoking or the nicotine gum. When all data were analyzed together, plasma nicotine levels and blood pressure were both independent predictors of endothelial function (p < 0.001 for both). In conclusion, cigarette smoking induced a dose-dependent attenuation in EDV, being maximal shortly after initiation of smoking and persisting up to 30-50 min. Nicotine chewing gum induced a similar impairment in EDV.