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document
Effect of systemic nitric oxide synthase inhibition on postexercise hypotension in humans . An acute bout of aerobic exercise results in a reduced blood pressure that lasts several hours . Animal studies suggest this response is mediated by increased production of nitric oxide . We tested the extent to which systemic nitric oxide synthase inhibition [ N ( G ) -monomethyl-L-arginine ( L-NMMA ) ] can reverse the drop in blood pressure that occurs after exercise in humans . Eight healthy subjects underwent parallel experiments on 2 separate days . The order of the experiments was randomized between sham ( 60 min of seated upright rest ) and exercise ( 60 min of upright cycling at 60 % peak aerobic capacity ) . After both sham and exercise , subjects received , in sequence , systemic alpha-adrenergic blockade ( phentolamine ) and L-NMMA . Phentolamine was given first to isolate the contribution of nitric oxide to postexercise hypotension by preventing reflex changes in sympathetic tone that result from systemic nitric oxide synthase inhibition and to control for alterations in resting sympathetic activity after exercise . During each condition , systemic and regional hemodynamics were measured . Throughout the study , arterial pressure and vascular resistances remained lower postexercise vs. postsham despite nitric oxide synthase inhibition ( e.g. , mean arterial pressure after L-NMMA was 108.0+/-2.4 mmHg postsham vs. 102.1+/-3.3 mmHg postexercise ; P < 0.05 ) . Thus it does not appear that postexercise hypotension is dependent on increased production of nitric oxide in humans .
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Intervention_Pharmacological
nitric oxide synthase
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Intervention_Physical
( 60 min of seated upright rest
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Intervention_Physical
( 60 min of upright cycling at 60 % peak aerobic capacity )
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Outcome_Physical
blood pressure
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Outcome_Physical
blood pressure
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Outcome_Physical
systemic and regional hemodynamics
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Outcome_Physical
arterial pressure and vascular resistances
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Outcome_Mental
nitric oxide synthase
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Outcome_Other
mean arterial pressure after L-NMMA
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Outcome_Physical
postexercise hypotension
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Outcome_Mental
production of nitric oxide
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Participant_Condition
postexercise hypotension
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Participant_Sample-size
Eight