Post-occlusion brachial artery vasodilatation after ischaemic handgrip exercise is nitric oxide mediated

Flow-mediated vasodilatation (FMD) of the brachial artery is used as a measure to quantify endothelial dysfunction. However, FMD after occlusion only is small in healthy people over middle age, but can be increased after handgrip exercise. The aim of this study was to evaluate whether postocclusion vasodilatation after handgrip exercise is mediated by nitric oxide (NO). High frequency ultrasound was used to measure brachial artery diameter at rest and after reactive hyperaemia with and without handgrip exercise during NaCl or NG-monomethyl-L-arginine (L-NMMA) infusion in healthy 60-year-old men. Postocclusion vasodilation was significantly larger after handgrip exercise compared with occlusion only (P=0.0078). Postocclusion vasodilatation was significantly lower after ischaemic handgrip exercise during intra-arterial infusion of L-NMMA compared with infusion of NaCl (P = 0.039). It may be concluded that the increased postocclusion brachial artery vasodilatation observed after ischaemic handgrip exercise is at least partly NO mediated. This modification of the investigation procedure may improve our ability to quantify FMD in subjects with and without vascular disease.