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Introduction: Among the extrapulmonary manifestations of COPD, dysfunction and loss of muscle mass/weight are those that have the greatest impact on the quality of life of patients. Our objective was to evaluate the molecular mechanisms that are potentially implicated in the limited development of muscle mass in the diaphragm and gastrocnemius of mice with experimentally-induced emphysema., Methods: An experimental model in mice, in which emphysema was induced by means of the local instillation of elastase (n=6), while saline was administered to the controls (n=7). We determined the levels of oxidative stress, proteolytic systems, signaling pathways, growth factors and cell differentiation (western-blot) in the diaphragm and gastrocnemius of all the mice after 34 weeks., Results: Upon comparing the mice with emphysema with the controls, the following findings were observed: (1) lower total body weight and lower weight of the diaphragm and gastrocnemius; (2) in the diaphragm, the levels of protein oxidation were increased, the mitochondrial antioxidant systems reduced, the levels of myostatin and of the ERK1/2 and FoxO1 signaling pathways were higher, and the myosin content was lower (67%); and (3) in the gastrocnemius of the emphysematous mice, the cytosolic antioxidants were decreased and the levels of myostatin and of the JNK and NF-kB signaling pathways were increased., Conclusions: The reduction of the myosin content observed in the diaphragm of mice with emphysema could explain their smaller size. Oxidative stress, myostatin and FoxO could be implicated in the loss of this structural protein., (Copyright © 2011 SEPAR. Published by Elsevier Espana. All rights reserved.)

Objective: Various methods have been used to obtain samples to study the structure of human respiratory muscles and the expression of diverse substances in them. Samples are most often obtained from autopsies, from muscle biopsies during thoracotomy performed because of a localized pulmonary lesion (TLL), and from ambulatory thoracoscopic biopsy in patients free of comorbidity (AT). The disadvantage of the first 2 of these methods lies in the possibility of interference from factors related to the patient's death in the first case or from the disease that necessitated surgery in the second. Although AT is free from the disadvantages of the other 2 methods, it is impossible to obtain samples of the diaphragm the principal respiratory muscle with this procedure. The objective of this study was to analyze the fibrous structure of the external intercostal muscle of patients with chronic obstructive pulmonary disease and to quantify the expression of the principal inflammatory cytokine tumor necrosis factor alpha (TNF-alpha)- and of insulin-like growth factor (IGF-1) in the same muscle, comparing the results obtained with TLL and AT samples., Methods: Prospective and consecutive samples were taken of the external intercostal muscle (fifth space, anterior axillary line) in 15 patients with chronic obstructive pulmonary disease (mean [SD] age 66 [6] years; forced expiratory volume in 1 second 49% [9%] of predicted; PaO2 75 [9] mm Hg). Samples were taken during TLL (8 patients, all with pulmonary neoplasms but carefully selected in order to rule out systemic effects) or TA (7 patients). Patients with serious comorbidity were excluded from the second group. Samples were processed for structural analysis of fibers (immunohistochemical and enzymatic histochemical) and genetic expression of TNF-alpha and IGF-1 (real-time polymerase chain reaction)., Results: No differences in the structure of fibers were found between the 2 groups. No differences were observed in the expression of TNF-alpha or IGF-1., Conclusions: Using rigorous criteria, the TLL method appears to be suitable for studying the structural characteristics and expression of inflammatory cytokines and growth factors in the external intercostal muscle. Moreover, it can also be inferred that TLL is probably also useful for obtaining samples of the diaphragm, a muscle which cannot currently be sampled by any alternative method.

Unlabelled: Changes in lung function have been related to adaptive structural modifications in respiratory muscles., Objective: To evaluate the capillary density (Dcap) of the external intercostal muscle in patients with chronic obstructive pulmonary disease (COPD), and its possible relation to respiratory function., Methods: Forty-two individuals (61 +/- 9 years old) underwent conventional lung function testing and evaluation of respiratory muscles (maximum pressures at rest and a tolerance test using Martyn's technique). The sample included 10 subjects with normal lung function and 32 COPD patients (FEV1 between 13 and 78% of reference), in stable phase and with no respiratory insufficiency (PaO2 > 60 mmHg). A local biopsy of the external intercostal muscle was taken from all subjects at the fifth intercostal space (anterior axillary [correction of axile]) on the non-dominant side. The sample was processed for morphometry and fiber typing with ATPase staining and for quantifying capillarity with Gomori's trichrome staining., Results: The mean diameter was 61 +/- 10 micrograms, with type I fibers predominating (56 +/- 11%). Dcap was 2.8 +/- 0.6 capillaries/fiber (equivalent to 1.02 +/- 0.37 capillaries/mm2 of fibrillary surface). The number of capillaries/fiber was significantly higher in patients with severe COPD (FEV1 < 50% ref) than in controls (3.0 +/- 0.6 versus 2.3 +/- 0.5, p < 0.01) and was inversely related to FEV1 (r = -0.395, p < 0.01). Muscle capillarity was unrelated to other function variables, including markers of respiratory muscle function and gas exchange., Conclusion: The structural remodelling of external intercostal muscles in COPD patients also includes an increase in density of interfibrillary capillaries. This increase is proportional to the severity of obstruction and probably reflects an adaptive phenomenon.

The morphological examination of respiratory muscle can be affected by muscular contraction following biopsy. Most morphometric studies of respiratory muscles, however, have been carried out without taking into account this factor, the effect of which can be reduced by using relaxants when taking samples. Objective. To examine the effect of using a relaxant in the morphometric analysis of muscle fibers. We examined 31 muscle samples from 7 patients. Immediately after removal, each pipe was divided in half. One was placed in an isotonic physiological solution and the other in a solution of curare 0.02%. Later, both samples were processed for morphometric study with ATP-ase, NADTH and PAS tincture. Morphological data recorded for the different types of fibers included measurement of minimum diameter (Dmin), atrophy and hypertrophy indices (AI and HI) and heterogeneity of distribution (SDDmin). The Dmin was smaller in fibers transported in a curare solution than in those transported in physiological solution (67 +/- 2 microns vs. 71 +/- microns, p < 0.05). The same was true of SDDmin (13 +/- 3 vs. 12 +/- 3, p < 0.05), HI (300 +/- 88 vs. 457 +/- 107, p < 0.05). Likewise, we found a similar direct correlation between size of fibers processed with physiological solution and those processed in curare (Dmin, r = 0.731, p < 0.001; HI, r = 0.827, p < 0.001; SDDmin, r = 0.636, p < 0.0001). The use of relaxants in processing muscle samples prevents contraction and should be used systematically in the morphological analysis of muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)