Submitted on March 27, 2008
Revised on June 23, 2008
Accepted on July 14, 2008
Altered Metabolic and Transporter Characteristics of Vastus Lateralis in Chronic Obstructive Pulmonary Disease
Howard J. Green1*, Margaret E. Burnett1, C. L. D'Arsigny2, Denis E O'Donnell3, J. Ouyang1, and Katherine A Webb3
1 University of Waterloo
2 Queens University
3 Queen's University
* To whom correspondence should be addressed. E-mail: green{at}healthy.uwaterloo.ca.
To investigate energy metabolic and transporter characteristics in resting muscle of patients with moderate to severe chronic obstructive pulmonary disease (mean ± SE; FEV1=42±6.0%; COPD), tissue was extracted from resting vastus lateralis (VL) of 9 COPD and compared to 12 healthy controls (FEV1 =114±3.4%; CON). As compared to CON, lower (P<0.05) concentrations (mmol.kg-1 d.w.) of ATP (19.6 ± 0.65 vs 17.8 ± 0.69) and phosphocreatine (81.3 ± 2.3 vs 69.1 ± 4.2) were observed in COPD which occurred in the absence of differences in the total adenine nucleotide and total creatine pools. Higher concentrations were observed in COPD for several glycolytic metabolites (G-1-P, G-6-P, F-6-P, pyruvate ) but not lactate. Glycogen storage was not affected by the disease (289 ± 20 vs 269 ± 20 mmol glucosyl units.kg-1 d.w). Although no difference between groups was observed for the glucose transporter, GLUT1, GLUT4 was reduced by 28% in COPD. For the monocarboxylate transporters, MCT4 was 35% lower in COPD, with no differences observed for MCT1. These results indicate that in resting VL, moderate to severe COPD results in a reduction in phosphorylation potential, an apparent elevation of glycolytic flux rate and a potential defect in glucose and lactate transport as a result of reduced levels of the principal isoforms.
