Four weeks of cycle training increases basal production of nitric oxide from the forearm. Kingwell, Bronwyn A., Bridget Sherrard, Garry L. Jennings, Anthony M. Dart. Alfred and Baker Medical Unit, Alfred Hospital and Baker Medical Research Institute
APStracts 3:0445H, 1996.
The purpose of this study was to determine whether non-trained vascular beds might contribute to the beneficial effects of exercise including reduced blood pressure by enhanced nitric oxide production. Thirteen healthy, sedentary male volunteers performed four weeks each of normal sedentary activity and four weeks of cycle training in a randomised order. At the end of each intervention venous occlusion plethysmography was used to study the forearm blood flow responses to intra arterial infusions of the nitric oxide synthase inhibitor NG -monomethyl L-arginine (L-NMMA), acetylcholine and sodium nitroprusside. Training increased maximum workload and maximal oxygen consumption while intra brachial blood pressure was reduced. L-NMMA caused a greater vasoconstriction after training (P=0.004). Net nitrate/nitrite consumption by the forearm was less after training both prior to and after administration of L-NMMA (P=0.04), consistent with increased nitrate/nitrite production from nitric oxide metabolism. There was no difference in response to acetylcholine or sodium nitroprusside between the two states. Preliminary studies showed an increase in forearm blood flow and blood viscosity after cycling suggesting that elevated shear stress in this vascular bed may contribute to endothelial adaptation and the cardiovascular protective effects of exercise training. 

Received 25 June 1996; accepted in final form 9 October 1996.
APS Manuscript Number H566-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996