Document Detail


Daily exercise attenuates the sympathetic nerve response to exercise by enhancing cardiac afferents.
MedLine Citation:
PMID:  9321855     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
"Central command" may initiate the sympathoexcitatory responses at the onset of exercise by shifting the operating point of the arterial baroreflex toward higher pressures. Daily exercise (DE) attenuates the sympathoexcitatory responses to submaximal exercise. This DE-induced adaptation may be due, in part, to an enhanced inhibitory influence of cardiac afferents. This is suggested because cardiac afferents exert a tonic inhibitory influence on the arterial baroreflex which is enhanced by DE. Therefore, the influence of cardiac afferents on the regulation of renal sympathetic nerve activity (RSNA) during exercise was examined in a group of sedentary and age-matched DE rabbits. The rabbits were instrumented with a Silastic catheter inserted into the pericardial sac, electrodes around the renal sympathetic nerves, and catheters in the femoral artery and vein. In the sedentary rabbits, treadmill exercise (12 m/min, 20% grade) significantly increased mean arterial pressure (delta 18 +/- 3 mmHg), heart rate (delta 36 +/- 3 beats/min), and RSNA (delta 295 +/- 23%). More importantly, cardiac afferent blockade (2% intrapericardial procainamide) did not significantly alter the RSNA response to exercise in the sedentary rabbits. DE did not alter the mean arterial pressure (delta 15 +/- 1 mmHg) or heart rate (delta 55 +/- 8 beats/min) response to exercise; however, RSNA (delta 252 +/- 9%) was significantly reduced. In contrast to the sedentary rabbits, cardiac afferent blockade in the DE rabbits significantly increased the RSNA response to exercise (delta 417 +/- 30%). These results suggest that DE attenuates the RSNA response to dynamic exercise due, in part, to an enhanced inhibitory influence of cardiac afferents.
Authors:
S E DiCarlo; L K Stahl; V S Bishop
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Sep 
Date Detail:
Created Date:  1997-10-23     Completed Date:  1997-10-23     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H1606-10     Citation Subset:  IM; S    
Affiliation:
Department of Physiology, Northeastern Ohio Universities College of Medicine, Rootstown 44272, USA.
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MeSH Terms
Descriptor/Qualifier:
Afferent Pathways
Animals
Baroreflex
Blood Pressure
Femoral Artery / physiology
Femoral Vein / physiology
Heart / innervation,  physiology*
Heart Rate
Kidney / innervation
Physical Conditioning, Animal / physiology*
Rabbits
Sympathetic Nervous System / physiology*
Grant Support
ID/Acronym/Agency:
HL-12415/HL/NHLBI NIH HHS; HL-45245/HL/NHLBI NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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