TY - JOUR

T1 - Microvascular function is impaired after short-term immobilization in healthy men

AU - Rytter, Nicolai

AU - Piil, Peter

AU - Carter, Howard

AU - Nyberg, Michael Permin

AU - Hellsten, Ylva

AU - Gliemann, Lasse

N1 - CURIS 2020 NEXS 298

PY - 2020

Y1 - 2020

N2 - Purpose: We examined whether two weeks of one-leg immobilization would impair leg microvascular function and to what extent a subsequent period of intense aerobic cycle training could restore function.Methods: Study participants were healthy young males (n=12; 20-24 years of age). Leg microvascular function was determined before the intervention, after the immobilization period and after a four-week exercise training period. Microvascular function was assessed as the vasodilator response to intra-arterial infusion of acetylcholine, sodium nitroprusside and as the vasoconstrictor response to endogenous noradrenaline release induced by tyramine infusion. Vasodilator enzymes as well as pro- and antioxidant enzymes were assessed by protein analysis in skeletal muscle samples; endothelial nitric oxide synthase NADPH oxidase (NOX p67phox and NOX gp91phox) and superoxide dismutase 2 (SOD2).Results: The acetylcholine induced change in vascular conductance was reduced after the two weeks of immobilization (P = 0.003), tended to increase after the subsequent four weeks of exercise training (P = 0.061) and was back to baseline levels. Plasma prostacyclin levels in response to acetylcholine infusion were lower after immobilization than before (P = 0.041). The changes in vascular conductance with sodium nitroprusside and tyramine were similar during all conditions. Skeletal muscle protein levels of eNOS in the experimental leg were unchanged with immobilization and subsequent training but increased 47% in the control leg with training (P = 0.002). NOX p67phox, NOX gp91phox, and SOD2 in the experimental leg remained unaltered with immobilization and SOD2 were higher than pre-immobilization after four weeks of training (P < 0.001).Conclusion: The study shows that two weeks of immobilization impairs leg microvascular endothelial function and prostacyclin formation but that four weeks of intense aerobic exercise training restores the function. The underlying mechanism may reside in the prostacyclin system.

AB - Purpose: We examined whether two weeks of one-leg immobilization would impair leg microvascular function and to what extent a subsequent period of intense aerobic cycle training could restore function.Methods: Study participants were healthy young males (n=12; 20-24 years of age). Leg microvascular function was determined before the intervention, after the immobilization period and after a four-week exercise training period. Microvascular function was assessed as the vasodilator response to intra-arterial infusion of acetylcholine, sodium nitroprusside and as the vasoconstrictor response to endogenous noradrenaline release induced by tyramine infusion. Vasodilator enzymes as well as pro- and antioxidant enzymes were assessed by protein analysis in skeletal muscle samples; endothelial nitric oxide synthase NADPH oxidase (NOX p67phox and NOX gp91phox) and superoxide dismutase 2 (SOD2).Results: The acetylcholine induced change in vascular conductance was reduced after the two weeks of immobilization (P = 0.003), tended to increase after the subsequent four weeks of exercise training (P = 0.061) and was back to baseline levels. Plasma prostacyclin levels in response to acetylcholine infusion were lower after immobilization than before (P = 0.041). The changes in vascular conductance with sodium nitroprusside and tyramine were similar during all conditions. Skeletal muscle protein levels of eNOS in the experimental leg were unchanged with immobilization and subsequent training but increased 47% in the control leg with training (P = 0.002). NOX p67phox, NOX gp91phox, and SOD2 in the experimental leg remained unaltered with immobilization and SOD2 were higher than pre-immobilization after four weeks of training (P < 0.001).Conclusion: The study shows that two weeks of immobilization impairs leg microvascular endothelial function and prostacyclin formation but that four weeks of intense aerobic exercise training restores the function. The underlying mechanism may reside in the prostacyclin system.

KW - Faculty of Science

KW - Inactivity

KW - Exercise training

KW - Skeletal muscle

KW - eNOS

KW - Tyramine

U2 - 10.1249/MSS.0000000000002369

DO - 10.1249/MSS.0000000000002369

M3 - Journal article

C2 - 32496738

VL - 52

SP - 2107

EP - 2116

JO - Medicine and Science in Sports and Exercise

JF - Medicine and Science in Sports and Exercise

SN - 0195-9131

IS - 10

ER -