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Repeated bouts of moderate-intensity aerobic exercise reduce airway reactivity in a murine asthma model.

Authors: Hewitt, M  Estell, K  Davis, IC  Schwiebert, LM 
Citation: Hewitt M, etal., Am J Respir Cell Mol Biol. 2010 Feb;42(2):243-9. Epub 2009 May 7.
Pubmed: (View Article at PubMed) PMID:19423772
DOI: Full-text: DOI:10.1165/rcmb.2009-0038OC

We have reported that moderate-intensity aerobic exercise training attenuates airway inflammation in mice sensitized/challenged with ovalbumin (OVA). The current study determined the effects of repeated bouts of aerobic exercise at a moderate intensity on airway hyperresponsiveness (AHR) in these mice. Mice were sensitized/challenged with OVA or saline and exercised at a moderate intensity 3 times/week for 4 weeks. At protocol completion, mice were analyzed for changes in AHR via mechanical ventilation. Results show that exercise decreased total lung resistance 60% in OVA-treated mice as compared with controls; exercise also decreased airway smooth muscle (ASM) thickness. In contrast, exercise increased circulating epinephrine levels 3-fold in saline- and OVA-treated mice. Because epinephrine binds beta(2)-adrenergic receptors (AR), which facilitate bronchodilatation, the role of beta(2)-AR in exercise-mediated improvements in AHR was examined. Application of the beta(2)-AR antagonist butoxamine HCl blocked the effects of exercise on lung resistance in OVA-treated mice. In parallel, ASM cells were examined for changes in the protein expression of beta(2)-AR and G-protein receptor kinase-2 (GRK-2); GRK-2 promotes beta(2)-AR desensitization. Exercise had no effect on beta(2)-AR expression in ASM cells of OVA-treated mice; however, exercise decreased GRK-2 expression by 50% as compared with controls. Exercise also decreased prostaglandin E(2) (PGE(2)) production 5-fold, but had no effect on E prostanoid-1 (EP1) receptor expression within the lungs of OVA-treated mice; both PGE(2) and the EP1 receptor have been implicated in beta(2)-AR desensitization. Together, these data indicate that moderate-intensity aerobic exercise training attenuates AHR via a mechanism that involves beta(2)-AR.

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CRRD Object Information
CRRD ID: 4145107
Created: 2010-10-25
Species: All species
Last Modified: 2010-10-25
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.