Document Detail

Effect of multiple denervations on the exercise hyperpnea in awake ponies.
MedLine Citation:
PMID:  7559236     Owner:  NLM     Status:  MEDLINE    
In three previously reported studies, we had documented that the normal exercise hyperventilation in ponies is accentuated by carotid body denervation (CBD), not affected by hilar nerve pulmonary vagal denervation (HND), and mildly attenuated by spinal cord ablation of the dorsal lateral columns at L2 (SA). In the present study, we hypothesized that if redundancy of control existed in exercising ponies, then multiple denervations of theoretically important pathways in the same animal might attenuate the ventilatory response to exercise in a way not predictable by the individual lesion experiments alone. There were three major findings in the various combinations of CBD, HND, and SA in ponies during treadmill exercise. First, the combination of CBD with HND or SA resulted generally in an accentuation of the hypocapnia during exercise that was predictable on the basis of CBD alone. However, in one pony that showed a hypercapnic exercise response after SA alone, CBD subsequently caused a greater exercise hypercapnia. Second, HND in a CBD or SA pony did not affect the exercise arterial PCO2 response, which is consistent with previous data showing the lack of an HND effect in otherwise intact ponies. Third, in ponies with all three denervations together, the predominant response was an increase, not a decrease, in the exercise hyperventilation; this increase was greater than that predicted from the individual lesions. We conclude that these data do not provide evidence of redundancy in mechanism for the exercise hyperpnea other than instances of carotid chemoreceptor error sensing when hypercapnia occurs during exercise.
L G Pan; H V Forster; R D Wurster; A G Brice; T F Lowry
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  79     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1995-11-14     Completed Date:  1995-11-14     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  302-11     Citation Subset:  IM    
Program in Physical Therapy, Marquette University, Milwaukee 53233, USA.
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MeSH Terms
Afferent Pathways / physiology
Carotid Body / physiology
Horses / physiology*
Hyperventilation / etiology*,  physiopathology
Physical Exertion*
Spinal Cord / physiology
Vagus Nerve / physiology
Grant Support
HL-25739/HL/NHLBI NIH HHS; S32-H107354-01A1-CLN-2/CL/CLC NIH HHS

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