Effects of nitric oxide synthase inhibitor on decrease in peripheral arterial stiffness with acute low-intensity aerobic exercise

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Abstract
We previously reported that even low-intensity, short-duration acute aerobic exercise decreases arterial stiffness. We aimed to test the hypothesis that the exercise-induced decrease in arterial stiffness is caused by the increased production of NO in vascular endothelium with exercise. Nine healthy men (age: ∼22–28 yr) performed a 5-min single-leg cycling exercise (30 W) in the supine position under an intravenous infusion of NG-monomethyl-l-arginine (l-NMMA; 3 mg/kg during the initial 5 min and subsequent continuous infusion of 50 μg·kg−1·min−1 in saline) or vehicle (saline) in random order on separate days. The pulse wave velocity (PWV) from the femoral to posterior tibial artery was measured on both legs before and after the infusion at rest and 2 min after exercise. Under the control condition, exercised leg PWV significantly decreased after exercise ( P < 0.05), whereas nonexercised leg PWV did not show a significant change throughout the experiment. Under l-NMMA administration, exercised leg PWV was increased significantly by the infusion ( P < 0.05) but decreased significantly after the exercise ( P < 0.05). Nonexercised leg PWV increased with l-NMMA administration and maintained a significantly higher level during the administration compared with baseline (before the infusion, all P < 0.05). The NO synthase blockade × time interaction on exercised leg PWV was not significant ( P = 0.706). These results suggest that increased production of NO is not a major factor in the decrease of regional arterial stiffness with low-intensity, short-duration aerobic exercise.