Relationship between changes in brachial artery flow-mediated dilation and basal release of nitric oxide in subjects with Type 2 diabetes.
Assessment of flow-mediated dilation (FMD) after forearm ischemia is widely used as a noninvasive bioassay of stimulated nitric oxide (NO)-mediated conduit artery vasodilator function in vivo. Whether this stimulated endothelial NO function reflects basal endothelial NO function is unknown. To test this hypothesis, retrospective analysis of randomized crossover studies was undertaken in 17 subjects with Type 2 diabetes; 9 subjects undertook an exercise training or control period, whereas the remaining 8 subjects were administered an angiotensin II receptor blocker or placebo. FMD was assessed by using wall tracking of high-resolution brachial artery ultrasound images in response to reactive hyperemia. Resistance vessel basal endothelium-dependent NO function was assessed by using intrabrachial administration of NG-monomethyl-L-arginine (L-NMMA) and plethysmographic assessment of forearm blood flow (FBF). FMD was higher after intervention compared with control/placebo (6.15+/-0.53 vs. 3.81+/-0.72%, P<0.001). There were no significant changes in the FBF responses to L-NMMA. Regression analysis between FMD and L-NMMA responses at entry to the study revealed an insignificant correlation (r=-0.10, P=0.7), and improvements in FMD with the interventions were not associated with changes in the L-NMMA responses (r=-0.04, P=0.9). We conclude that conduit artery-stimulated endothelial NO function (FMD) does not reflect basal resistance vessel endothelial NO function in subjects with Type 2 diabetes.
School of Sport and Exercise Science, Henry Cotton Bldg., 15-21 Webster St., Liverpool John Moores University, L32ET, United Kingdom, and Cardiac Transplant Unit, Royal Perth Hospital, Australia. d.j.green@ljmu.ac.uk
Daniel J
DJ
Green
Andrew J
AJ
Maiorana
Michael E
ME
Tschakovsky
Kyra E
KE
Pyke
Cara J
CJ
Weisbrod
Gerry
G
O'Driscoll
D001916:Brachial Artery / Q000187:drug effects / Q000502:physiology*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005542:Forearm / Q000098:blood supply; D006801:Humans; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D016032:Randomized Controlled Trials as Topic; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012044:Regression Analysis; D012189:Retrospective Studies; D014655:Vascular Resistance / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide