Document Detail

Onset of exercise shifts operating point of arterial baroreflex to higher pressures.
MedLine Citation:
PMID:  1733319     Owner:  NLM     Status:  MEDLINE    
This study was designed to test the hypothesis that the increase in sympathetic nerve activity (SNA) and mean arterial pressure (MAP) at the onset of exercise is dependent on a rapid upward shift of the operating point of the arterial baroreflex. To test this hypothesis, we recorded renal sympathetic nerve activity (RSNA) in 16 New Zealand White rabbits during treadmill running (12.6 m/min, 20% grade) under control conditions and during concomitant intravenous infusions of nitroglycerin (NTG) to attenuate the exercise pressor response. In the control condition, MAP increased 18 +/- 2 mmHg. This was associated with an increase in heart rate (HR) (104 +/- 4 beats/min) and RSNA (414 +/- 20%). The increases in RSNA (848 +/- 32%) and HR (155 +/- 5 beats/min) at the onset of exercise were significantly augmented when the rate of development of the exercise pressor response (0.3 +/- 0.03 to 0.12 +/- 0.01 mmHg/s) and the magnitudes of the pressor response (91 +/- 2 to 79 +/- 1 mmHg) were attenuated by infusions of NTG. These data suggest that at the onset of exercise the operating point of the arterial baroreflex is reset toward higher pressures. The MAP, RSNA, and HR responses to exercise were also determined in eight sinoaortic-denervated (SAD) rabbits. In the absence of a functional baroreflex, MAP (-46 +/- 2 mmHg), RSNA (-19 +/- 1%), and HR (-62 +/- 3 beats/min) decreased at the onset of exercise and recovered 1 min to -42 +/- 2, +13 +/- 1, and +9 +/- 1% of control, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
S E DiCarlo; V S Bishop
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  262     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1992 Jan 
Date Detail:
Created Date:  1992-02-25     Completed Date:  1992-02-25     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H303-7     Citation Subset:  IM; S    
Department of Physiology, Northeastern Ohio Universities, College of Medicine, Rootstown 44272.
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MeSH Terms
Arteries / physiology*
Blood Pressure*
Heart Rate
Kidney / physiology
Physical Exertion*
Pressoreceptors / physiology*
Reflex / physiology*
Sinus of Valsalva / physiology
Sympathetic Nervous System / physiology
Grant Support

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