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The carotid baroreflex is reset following prolonged exercise in humans.
MedLine Citation:
PMID:  20608902     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
AIM: Alterations in the carotid baroreflex (CBR) control of arterial pressure may explain the reduction in arterial pressure and left ventricular (LV) function after prolonged exercise. We examined the CBR control of heart rate (HR) and mean arterial pressure (MAP), in addition to changes in LV function, pre- to post-exercise.
METHODS: Seven males (age, mean ± SEM; 29 ± 4 years) completed 4 h of ergometer rowing at a workload of 10-15% below the lactate threshold. The CBR control of HR and MAP was assessed via the rapid neck-suction/pressure protocol. LV systolic function was measured by echocardiography, where ejection fraction (EF), the ratio of systolic blood pressure to end systolic volume (SBP/ESV) and stroke volume (SV) were estimated.
RESULTS: Following exercise MAP was reduced (12 ± 3%) and HR was elevated (35 ± 5%; P < 0.05). Furthermore, CBR control of MAP was relocated to the left on the stimulus-response curve (P < 0.05) demonstrating that the CBR operated around a lower arterial pressure. Concomitantly, LV systolic function was reduced, indicated by a decrease in EF (22 ± 2%), SBP/ESV (32 ± 14%) and SV (25 ± 5%, P < 0.05). The reduced EF and SBP/ESV were associated with the decreased MAP operating point (r² = 0.71 and r² = 0.47, respectively, P < 0.05).
CONCLUSION: The CBR is reset after prolonged exercise to a lower prevailing arterial pressure. This resetting of the CBR may contribute to the reduction arterial pressure and LV function after exercise.
Authors:
E C Hart; P Rasmussen; N H Secher; K P George; N T Cable; S Volianitis; R Shave
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Acta physiologica (Oxford, England)     Volume:  200     ISSN:  1748-1716     ISO Abbreviation:  Acta Physiol (Oxf)     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-09     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101262545     Medline TA:  Acta Physiol (Oxf)     Country:  England    
Other Details:
Languages:  eng     Pagination:  291-9     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors. Acta Physiologica © 2010 Scandinavian Physiological Society.
Affiliation:
Centre for Sports Medicine and Human Performance, Brunel University, London, UK. hart.emma@mayo.edu
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