Document Detail

Respiratory gas exchange and metabolic responses during exercise in McArdle's disease.
MedLine Citation:
PMID:  8226478     Owner:  NLM     Status:  MEDLINE    
During normal progressive exercise, the gas exchange anaerobic threshold occurs when CO2 production (VCO2) and ventilation (VE) increase so as to depart from a linear relationship to O2 consumption (VO2). This is thought to represent a gas exchange response to metabolic acidosis due to lactate accumulation. Patients with McArdle's disease have previously been reported to exhibit a steepened ventilatory response relative to VCO2, despite an inability to produce lactate. However, the VCO2 response has not been studied. We therefore investigated the VCO2-VO2 and VE-VO2 relationships in seven McArdle's disease patients and seven control subjects during symptom-limited maximal treadmill exercise. Analysis of gas exchange showed that whereas all control subjects had an easily identifiable anaerobic threshold, four of the patients had none and the other three displayed an attenuated threshold. The occurrence of the threshold in one patient was associated with a small rise in lactate and in another patient with an abrupt rise in leg discomfort, suggesting a pain response. Ammonia and the purine metabolite hypoxanthine were elevated during exercise in all patients, suggesting that ammonia may be a product of adenosine monophosphate degradation. Free fatty acid levels were also elevated, and a shift toward utilization of lipid may contribute to abnormal gas exchange responses. It is concluded that lactic acidosis contributes to the gas exchange anaerobic threshold but that other factors, such as discomfort, may be involved in the excess Ve seen during heavy exercise.
M Riley; D P Nicholls; A M Nugent; I C Steele; N Bell; P M Davies; C F Stanford; V H Patterson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  75     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1993 Aug 
Date Detail:
Created Date:  1993-12-03     Completed Date:  1993-12-03     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:  745-54     Citation Subset:  IM; S    
Royal Victoria Hospital, Belfast, United Kingdom.
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MeSH Terms
Ammonia / blood
Anaerobic Threshold / physiology
Carbon Dioxide / metabolism
Exercise / physiology*
Exercise Test
Glycogen Storage Disease Type V / metabolism,  pathology,  physiopathology*
Hypoxanthines / blood
Lactates / blood
Leg / physiology
Middle Aged
Muscles / pathology,  physiology
Oxygen Consumption / physiology
Pulmonary Gas Exchange / physiology*
Respiratory Mechanics / physiology
Reg. No./Substance:
0/Hypoxanthines; 0/Lactates; 124-38-9/Carbon Dioxide; 7664-41-7/Ammonia

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