ABSTRACT
Ohjective To study the effects of emphysema on peripheral skeletal muscle biomechanics,pathomorphology and oxidative metabolism in rats.Methods Twenty Sprague-Dawley rats were used and randomized equally into a control group and an emphysema group.A dose of 40 U/100 g body weight of porcine pancreatic elastase was instilled into the trachea of the animals of the emphysema group to model emphysema,while the same volume of saline was instilled into those of the control group.Twenty weeks after instillation,in situ mechanical properties of gastrocnemius were evaluated.Gastrocnemius fiber type composition and capillary density (CD) were assessed by using ATPase staining.Lipofuscin accumulation (LI/F) was determined with the ferric-ferricyanide reduction test technique.Immunohistochemistry was used for the detection of nitric oxide synthases (NOS) in gastrocnemius.The muscle biopsy homogenate was used to measure the activity of superoxide dismutase (SOD),catalase (CAT),NOS,total antioxidant capacity (T-AOC) and the content of nitric oxide (NO).Results Emphysema increased fatigability and decreased the recovery rate of gastrocnemius muscle [(145.0 ± 55.4) s vs (55.2 ± 29.3)s,P ＜ 0.05].Compared to control,the gastrocnemius muscle in rats with emphysema had a lower CD [(513.9±71.1)n/mm2 vs (578.6 ±59.9)n/mm2,P ＜0.05] and a decreased proportion of type I fibers [(16.0 ±5.0)％ vs (30.7 ±4.1) ％,P ＜0.05],with a reciprocal increase in type II b/x fibers [(27.3 ±4.8)％vs (11.0±3.2)％,P＜0.05].LI/F was higher (3.3±0.5 vsl.7±0.4,P＜0.05) and the activity of SOD,CAT and T-AOC was increased in emphysema group.Compared with control,rats with emphysema demonstrated a lower expression of endothelial NOS (eNOS) (1.9 ± 0.5 vs 3.4 ± 0.6,P ＜ 0.05),and an equivalent expression of neuronal NOS (nNOS) (4.7 ± 1.0 vs 5.1 ± 0.8,P ＞ 0.05) in the gastrocnemius muscle.The inducible NOS (iNOS) was not found in both groups.Conclusions Emphysema could induce biomechanical,pathomorphological and oxidative metabolic changes in peripheral skeletal muscle.