Document Detail


The effect of CO2 on the ventilatory sensitivity to rising body temperature during exercise.
MedLine Citation:
PMID:  21393474     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
We examined the degree to which ventilatory sensitivity to rising body temperature (the slope of the regression line relating ventilation and body temperature) is altered by restoration of arterial PCO(2) to the eucapnic level during prolonged exercise in the heat. Thirteen subjects exercised for ~60 min on a cycle ergometer at 50% of peak O(2) uptake, with and without inhalation of CO(2)-enriched air. The subjects began breathing CO(2)-enriched air at the point end-tidal PCO(2) started to decline. Esophageal temperature (T(es)), minute ventilation (V((.))(E)), tidal volume (V(T)), respiratory frequency (f(R)), respiratory gases, middle cerebral artery blood velocity and arterial blood pressure were recorded continuously. When V((.))(E), V(T), f(R), ventilatory equivalents for O(2) uptake (V((.))E/V((.))O(2)) and CO(2) output (V((.))E/V((.))(CO2)), were plotted against changes in T(es) from the start of the CO(2)-enriched air inhalation (ΔTes), the slopes of the regression lines relating V((.))E, VT, V((.))E/V((.))O2 and V((.))E/V((.))CO2 to ΔT(es) (ventilatory sensitivity to rising body temperature) were significantly greater when subjects breathed CO2-enriched air than when they breathed room air (V((.))E, 19.8 ± 10.3 vs. 8.9 ± 6.7 L(.)min(-1)(.)°C(-1); VT, 18 ± 120 vs. -81 ± 92 mL(.)°C(-1); V(.)(E)/V(.)(O2), 7.4 ± 5.5 vs. 2.6 ± 2.3 unit(.)°C(-1); V((.))E/V((.))(CO2), 7.6 ± 6.6 vs. 3.4 ± 2.8 unit(.)°C(-1)). The increase in V((.))E was accompanied by increases in V(T) and f(R). These results suggest that restoring arterial PCO(2) to nearly eucapnic levels increases ventilatory sensitivity to rising body temperature by around 3-fold.
Authors:
Keiji Hayashi; Yasushi Honda; Natsuki Miyakawa; Naoto Fujii; Masashi Ichinose; Shunsaku Koga; Narihiko Kondo; Takeshi Nishiyasu
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-10
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  -     ISSN:  1522-1601     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1University of Shizuoka.
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