Vastus lateralis Na(+)-K(+)-ATPase activity, protein, and isoform distribution in chronic obstructive pulmonary disease.

In this study we investigate the hypothesis that protein abundance, isoform distribution, and maximal catalytic activity of sodium-potassium-adenosine triphosphatase (Na(+)-K(+)-ATPase) would be altered in muscle of patients with moderate to severe chronic obstructive pulmonary disease (COPD). Tissue samples were obtained from the vastus lateralis of 10 patients with COPD (mean +/- SE: age = 67 +/- 2.9 years; FEV1 = 39 +/- 5.