Endothelium-derived nitric oxide activity in forearm vessels of tennis players

The aim of this study was to determine whether physical conditioning induced by a repetitive exercise stimulus would elicit changes in the response of forearm resistance vessels to an infusion of substances that modulate nitric oxide synthesis. Forearm blood flow responses to a 5-min ischemic stimulus and intrabrachial infusion of acetylcholine, sodium nitroprusside, and N-G-monomethyl-L-arginine were examined in the preferred and nonpreferred limbs of eight habitual tennis players. Forearm volume, girth, and grip strength were significantly greater in the preferred limb, indicating a bilateral difference in physical condition. This was associated with an enhanced reactive hyperemic response in the preferred limb (53.5 +/- 9.4 vs. 38.8 +/- 4.7 ml . 100 ml(-1). min(-1); P <0.05). No differences between the limbs were evident in response to acetylcholine, sodium nitroprusside, or N-G-monomethyl-L-arginine. These results suggest that exercise training enhances the peak vasodilator capacity of the vasculature without influencing basal or stimulated activity of the nitric oxide dilator system in vivo.