Document Detail


Exercise training prevents skeletal muscle afferent sensitization in rats with chronic heart failure.
MedLine Citation:
PMID:  22496362     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
An exaggerated exercise pressor reflex (EPR) contributes to exercise intolerance and excessive sympathoexcitation in the chronic heart failure (CHF) state, which is prevented by exercise training (ExT) at an early stage in the development of CHF. We hypothesized that ExT has a beneficial effect on the exaggerated EPR by improving the dysfunction of muscle afferents in CHF. We recorded the discharge of mechanically sensitive (group III) and metabolically sensitive (group IV) afferents in response to static contraction, passive stretch, and hindlimb intra-arterial injection of capsaicin in sham+sedentary (Sed), sham+ExT, CHF+Sed, and CHF+ExT rats. Compared with sham+Sed rats, CHF+Sed rats exhibited greater responses of group III afferents to contraction and stretch, whereas the responses of group IV afferents to contraction and capsaicin were blunted. ExT prevented the sensitization of group III responses to contraction or stretch and partially prevented the blunted group IV responses to contraction or capsaicin in CHF rats. Furthermore, we investigated whether purinergic 2X (P2X) and transient receptor potential vanilloid 1 (TRPV1) receptors mediate the altered sensitivity of muscle afferents by ExT in CHF. We found that the upregulated P2X and downregulated TRPV1 receptors in L4/5 dorsal root ganglia of CHF rats were normalized by ExT. Hindlimb intra-arterial infusion of a P2X antagonist attenuated the group III response to contraction or stretch in CHF rats to a greater extent than in sham rats, which was normalized by ExT. These findings suggest that ExT improves the abnormal sensitization of muscle afferents in CHF at least, in part, via restoring the dysfunction of P2X and TRPV1 receptors.
Authors:
Han-Jun Wang; Yu-Long Li; Irving H Zucker; Wei Wang
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-04-11
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  302     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-06-04     Completed Date:  2012-11-29     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1260-70     Citation Subset:  IM    
Affiliation:
Dept. of Cellular and Integrative Physiology, Univ. of Nebraska Medical Center, Omaha, NE 68198, USA.
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MeSH Terms
Descriptor/Qualifier:
Afferent Pathways / drug effects,  physiopathology*
Animals
Blotting, Western
Capsaicin / pharmacology
Chronic Disease
Decerebrate State / physiopathology
Electrophysiology
Heart Failure / physiopathology*
Hindlimb / physiopathology
Immunohistochemistry
Muscle Contraction / physiology*
Muscle, Skeletal / drug effects,  physiopathology*
Physical Conditioning, Animal / physiology*
Rats
Rats, Sprague-Dawley
Receptors, Purinergic P2X / metabolism
TRPC Cation Channels / metabolism
Grant Support
ID/Acronym/Agency:
P01 HL-62222/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Receptors, Purinergic P2X; 0/TRPC Cation Channels; 404-86-4/Capsaicin
Comments/Corrections

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