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Preserved contribution of nitric oxide to baseline vascular tone in deconditioned human skeletal muscle
Author(s) -
Bleeker Michiel W. P.,
Kooijman Miriam,
Rongen Gerard A.,
Hopman Maria T. E.,
Smits Paul
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.085936
Subject(s) - deconditioning , medicine , vasodilation , vascular resistance , cardiology , hemodynamics
Deconditioning is a risk factor for cardiovascular disease. Exercise reduces this risk, possibly by improving the vascular endothelial nitric oxide (NO) pathway. The effect of deconditioning on the NO pathway is largely unknown. This study was designed to assess baseline NO availability in the leg vascular bed after extreme, long‐term deconditioning (spinal cord‐injured individuals, SCI) as well as after moderate, short‐term deconditioning (4 weeks of unilateral lower limb suspension, ULLS). For this purpose, seven SCI were compared with seven matched controls. Additionally, seven healthy subjects were studied pre‐ and post‐ULLS. Leg blood flow was measured by venous occlusion plethysmography at baseline and during infusion of 5 incremental dosages of N G ‐monomethyl‐ l ‐arginine ( l ‐NMMA) into the femoral artery. Sodium nitroprusside (SNP) was infused to test vascular responsiveness to NO. Baseline leg vascular resistance tended to be higher in SCI compared with controls (37 ± 4 versus 31 ± 2 arbitrary units (AU), P = 0.06). Deconditioning altered neither the vasoconstrictor response to l ‐NMMA (increase in resistance in SCI versus controls: 102 ± 33% versus 69 ± 9%; pre‐ versus post‐ULLS: 95 ± 18% versus 119 ± 15%), nor the vascular responsiveness to NO. In conclusion, two human in vivo models of deconditioning show a preserved baseline NO availability in the leg skeletal muscle vascular bed.