Vasoconstrictor responsiveness during hyperbaric hyperoxia in contracting human muscle

被引:15
作者
Casey, Darren P. [1 ]
Joyner, Michael J. [1 ]
Claus, Paul L. [2 ]
Curry, Timothy B. [1 ]
机构
[1] Mayo Clin, Dept Anesthesiol, Rochester, MN 55905 USA
[2] Mayo Clin, Div Prevent Occupat & Aerosp Med, Rochester, MN 55905 USA
基金
美国国家卫生研究院;
关键词
alpha-adrenergic; vasoconstriction; skeletal muscle blood flow; HUMAN SKELETAL-MUSCLE; LEG BLOOD-FLOW; NITRIC-OXIDE; HYPOXIC EXERCISE; SYMPATHETIC VASOCONSTRICTION; ENDOTHELIN-1; CONTRIBUTES; OXYGEN-TENSION; HEALTHY HUMANS; VASCULAR-TONE; ATP RELEASE;
D O I
10.1152/japplphysiol.01197.2012
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Vasoconstrictor responsiveness during hyperbaric hyperoxia in contracting human muscle. J Appl Physiol 114: 217-224, 2013. First published November 8, 2012; doi:10.1152/japplphysiol.01197.2012.-Large increases in systemic oxygen content cause substantial reductions in exercising forearm blood flow (FBF) due to increased vascular resistance. We hypothesized that 1) functional sympatholysis (blunting of sympathetic alpha-adrenergic vasoconstriction) would be attenuated during hyperoxic exercise and 2) alpha-adrenergic blockade would limit vasoconstriction during hyperoxia and increase FBF to levels observed under normoxic conditions. Nine male subjects (age 28 +/- 1 yr) performed forearm exercise (20% of maximum) under normoxic and hyperoxic conditions. Studies were performed in a hyperbaric chamber at 1 atmosphere absolute (ATA; sea level) while breathing 21% O-2 and at 2.82 ATA while breathing 100% O-2 (estimated change in arterial O-2 content similar to 6 ml O-2/100 ml). FBF (ml/min) was measured using Doppler ultrasound. Forearm vascular conductance (FVC) was calculated from FBF and blood pressure (arterial catheter). Vasoconstrictor responsiveness was determined using intra-arterial tyramine. FBF and FVC were substantially lower during hyperoxic exercise than normoxic exercise (similar to 20-25%; P < 0.01). At rest, vasoconstriction to tyramine (% decrease from pretyramine values) did not differ between normoxia and hyperoxia (P > 0.05). During exercise, vasoconstrictor responsiveness was slightly greater during hyperoxia than normoxia (-22 +/- 3 vs. -17 +/- 2%; P < 0.05). However, during alpha-adrenergic blockade, hyperoxic exercise FBF and FVC remained lower than during normoxia (P < 0.01). Therefore, our data suggest that although the vasoconstrictor responsiveness during hyperoxic exercise was slightly greater, it likely does not explain the majority of the large reductions in FBF and FVC (similar to 20-25%) during hyperbaric hyperoxic exercise.
引用
收藏
页码:217 / 224
页数:8
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