Aging-Associated Endothelial Dysfunction in Humans Is Reversed by L-Arginine

ObjectivesThis study investigated the hypothesis that aging selectively impairs endothelium-dependent function, which may be reversible by administration of L-arginine.BackgroundAn impaired response to acetylcholine with aging has been demonstrated in humans. However, the mechanisms underlying this impaired response of the coronary microvasculature remain to be determined.MethodsWe infused the endothelium-independent vasodilators papaverine and glyceryl trinitrate (GTN) and the endothelium-dependent vasodilator acetylcholine (1,3,10 and 30 /g/min) into the left coronary artery of 34 patients (27 to 73 years old) with atypical chest pain, negative exercise test results, completely normal findings on coronary angiography and no coronary risk factors. Coronary blood flow was measured with an intracoronary Doppler catheter. The papaverine and acetylcholine infusions were repeated in 14 patients (27 to 73 years old) after an intracoronary infusion of L-arginine (160 μmol/min for 20 min).ResultsThere was a significant negative correlation between aging and the peak coronary blood flow response evoked by acetylcholine (r =-0.73, p < 0.0001). However, there was no correlation between aging and the peak coronary blood flow response to papaverine (r =-0.04, p = 0.82) and GTN (r = -0.24, p = 0.17). The peak coronary blood flow response evoked by acetylcholine correlated significantly with aging before L-arginine infusion (r =-0.87, p < 0.0001), but this negative correlation was lost after L-arginine infusion (r =-0.37, p = 0.19).ConclusionsThe results suggest that aging selectively impairs endothelium-dependent coronary microvascular function and that this impairment can be restored by administration of L-arginine, a precursor of nitric oxide