Pulmonary emphysema decreases hamster skeletal muscle oxidative enzyme capacity

Abstract

Skeletal muscle oxidative enzyme capacity is impaired in patients suffering from emphysema and chronic obstructive pulmonary disease. This effect may result as a consequence of the physiological derangements because of the emphysema condition or, alternatively, as a consequence of the reduced physical activity level in these patients. To explore this issue, citrate synthase (CS) activity was measured in selected hindlimb muscles and the diaphragm of Syrian Golden hamsters 6 mo after intratracheal instillation of either saline (Con, n = 7) or elastase [emphysema (Emp); 25 units/100 g body weight, n = 8]. Activity level was monitored, and no difference between groups was found. Excised lung volume increased with emphysema (Con, 1.5 +/- 0.3 g; Emp, 3.0 +/- 0.3 g, P < 0.002). Emphysema significantly reduced CS activity in the gastrocnemius (Con, 45.1 +/- 2.0; Emp, 39.2 +/- 0.8 micromol . min-1 . g wet wt-1, P < 0.05) and vastus lateralis (Con, 48.5 +/- 1.5; Emp, 44.9 +/- 0.8 micromol . min-1 . g wet wt-1, P < 0.05) but not in the plantaris (Con, 47.4 +/- 3.9; Emp, 48.0 +/- 2.1 micromol . min-1 . g wet wt-1, P < 0.05) muscle. In contrast, CS activity increased in the costal (Con, 61.1 +/- 1.8; Emp, 65.1 +/- 1.5 micromol . min-1 . g wet wt-1, P < 0.05) and crural (Con, 58.5 +/- 2.0; Emp, 65.7 +/- 2.2 micromol . min-1 . g wet wt-1, P < 0.05) regions of the diaphragm. These data indicate that emphysema per se can induce decrements in the oxidative capacity of certain nonventilatory skeletal muscles that may contribute to exercise limitations in the emphysematous patient.