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document
Effects of nitric oxide synthase inhibition on cutaneous vasodilation in response to acupuncture stimulation in humans . OBJECTIVES The aim of the present study was to elucidate the mechanism of cutaneous vasodilation following acupuncture stimulation by investigating the roles of nitric oxide ( NO ) and axon reflex vasodilation . METHODS The subjects were 17 healthy male volunteers . The role of NO was investigated by administering N ( G ) -nitro-l-arginine methyl ester hydrochloride ( L-NAME , 20 mM ) , an NO synthase inhibitor or Ringer 's solution ( control site ) , via intradermal microdialysis ( protocol 1 ; n=7 ) . The role of axon reflex vasodilation by local sensory neurones was investigated by comparing vasodilation at sites treated with 'eutectic mixture of local anaesthetics ' ( EMLA ) cream ( 2.5 % lidocaine and 2.5 % prilocaine ) with untreated sites ( control site ) ( protocol 2 ; n=10 ) . After 5 min of baseline recording , acupuncture was applied to PC4 and a control site in proximity to PC4 for 10 min and scanning was performed for 60 min after acupuncture stimulation . Skin blood flow ( SkBF ) was evaluated by laser Doppler perfusion imaging . Cutaneous vascular conductance ( CVC ) was calculated from the ratio of SkBF to mean arterial blood pressure . RESULTS In the first protocol , sites administered L-NAME showed significant reductions in CVC responses following acupuncture stimulation compared to control sites ( administered Ringer 's solution ) ( p < 0.05 ) . In the second protocol , changes in CVC responses after acupuncture stimulation did not differ significantly between treated sites with EMLA cream and untreated sites ( p > 0.05 ) . CONCLUSIONS These data suggest that cutaneous vasodilation in response to acupuncture stimulation may not occur through an axon reflex as previously reported . Rather , NO mechanisms appear to contribute to the vasodilator response .
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Intervention_Pharmacological
nitric oxide synthase inhibition
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Intervention_Physical
acupuncture
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Intervention_Pharmacological
N ( G ) -nitro-l-arginine methyl ester hydrochloride ( L-NAME
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Intervention_Pharmacological
NO synthase inhibitor
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Intervention_Pharmacological
Ringer 's solution
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Intervention_Pharmacological
'eutectic mixture of local anaesthetics ' ( EMLA )
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Intervention_Pharmacological
lidocaine
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Intervention_Pharmacological
prilocaine
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Intervention_Physical
acupuncture
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Intervention_Pharmacological
Ringer 's
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Intervention_Pharmacological
EMLA
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Outcome_Physical
cutaneous vasodilation
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Outcome_Physical
Skin blood flow ( SkBF )
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Outcome_Physical
Doppler perfusion imaging
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Outcome_Physical
Cutaneous vascular conductance ( CVC )
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Outcome_Physical
CVC responses
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Outcome_Physical
changes in CVC responses
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Participant_Sample-size
17
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Participant_Condition
healthy
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Participant_Sex
male volunteers