title: Local adenosine receptor blockade accentuates the sympathetic responses to fatiguing exercise.
abstract: The role adenosine plays in evoking the exercise pressor reflex in humans remains controversial. We hypothesized that localized forearm adenosine receptor blockade would attenuate muscle sympathetic nerve activity (MSNA) responses to fatiguing handgrip exercise in humans. Blood pressure (Finometer), heart rate, and MSNA from the peroneal nerve were assessed in 11 healthy young volunteers during fatiguing isometric handgrip, postexercise circulatory occlusion (PECO), and passive muscle stretch during PECO. The protocol was performed before and after adenosine receptor blockade by local infusion of 40 mg aminophylline in saline via forearm Bier block (regional intravenous anesthesia). In the second experiment, the same amount of saline was infused via the Bier block. After aminophylline, the MSNA and blood pressure responses to fatiguing handgrip, PECO, and passive stretch (all P < 0.05) were significantly greater than during the control condition. Saline Bier block had no similar effects on the MSNA and blood pressure responses. These data suggest that adenosine receptor antagonism in the exercising muscles may accentuate sympathetic activation during fatiguing exercise.
authors.affiliation: Penn State Heart & Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Cui
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
authors.forename: Cheryl
authors.initials: C
authors.lastname: Blaha
authors.forename: Jonathan
authors.initials: J
authors.lastname: Yoder
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Gao
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Sinoway
mesh_terms: D000328:Adult; D000628:Aminophylline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D052580:Muscle Stretching Exercises; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D000628:Aminophylline
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