Peripheral muscle alterations in non-COPD smokers.
BACKGROUND
Although tobacco smoke is the main cause of COPD, relatively little attention has been paid to its potential damage to skeletal muscle. This article addresses the effect of smoking on skeletal muscle.


METHODS
The vastus lateralis muscle was studied in 14 non-COPD smokers (FEV(1)/FVC, 78 +/- 5%) and 20 healthy control subjects (FEV(1)/FVC, 80 +/- 3%). Muscular structure, enzyme activity, constitutive and inducible nitric oxide (NO) synthases (endothelial NO oxide synthase [eNOS], neuronal NO synthase [nNOS] and inducible NO synthase [iNOS]), nitrites, nitrates, nitrotyrosine, and the presence of macrophages were analyzed.


RESULTS
In smokers, type I muscle fibers cross-sectional area was decreased, and a similar trend was found in type IIa fibers. Lactate dehydrogenase levels and the percentage of fibers with low oxidative and high glycolytic capacity were increased in smokers. nNOS (96.9 +/- 11.7 vs 125.4 +/- 31.9 ng/mg protein; p < 0.01) and eNOS (38.9 +/- 11.0 vs 45.2 +/- 7.7 ng/mg protein [+/- SD]; p < 0.05) were lower in smokers, while fiber type distribution, capillarity measures, beta-hydroxy-acyl-CoA-dehydrogenase levels, iNOS, nitrite, nitrate, and nitrotyrosine levels, and macrophage number in the muscle tissue were similar to the nonsmoker subjects.


CONCLUSIONS
Smokers presented some alterations of skeletal muscle such as oxidative fiber atrophy, increased glycolytic capacity, and reduced expression of the constitutive NO synthases (eNOS and nNOS). The findings support some muscular structural and metabolic damage but not the presence of local inflammation in the smokers. In addition, they suggest a possible effect of tobacco smoke impairing the normal process of NO generation.
Montes de Oca
Maria
M
Pulmonary Division, Hospital Universitario de Caracas, Universidad Central de Venezuela, Los Chaguaramos, Caracas, Venezuela. mmdeoca@cantv.net
Loeb
Eduardo
E
Torres
Sonia H
SH
De Sanctis
Juan
J
Hernández
Noelina
N
Tálamo
Carlos
C
D006801:Humans; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000473:pathology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects*
D019001:Nitric Oxide Synthase