Muscle fiber type characteristics in females with chronic obstructive pulmonary disease. A preliminary study

Abstract

Chronic obstructive pulmonary disease (COPD) is known to elicit intrinsic abnormalities in male skeletal muscle. However, it is unclear to what extent these changes occur in women and whether they are fiber-type specific. We investigated fiber-type specific differences in selected histochemical properties in muscle obtained from women with moderate to severe COPD compared to healthy control (CON) women. Tissue was obtained from the vastus lateralis in five COPD patients (age 66.9 +/- 2.6 years; FEV1 = 43 +/- 7%) and eight CON (age 68 +/- 4.9 years; FEV1 = 113 +/- 4.2%). Compared to CON, the distribution (30.6 +/- 5.2 vs. 57.9 +/- 4.6%) and cross sectional area of type I (CSA, 5660 +/- 329 vs. 3586 +/- 257 microm2) and type IIA (2770 +/- 302 vs. 2099 +/- 206 microm2) were lower (P < 0.05) and higher (P < 0.05), respectively, in COPD. Disease state did not alter either the distribution or CSA of the IIA, IIAX or type X subtypes. Although differences were found between fiber types in the number of capillary contacts (n) (I > IIAX, IIX; IIA > IIX) and the capillaries per CSA (microm210(-3)) (I < IIA, IIAX, IIX), no differences were found between CON and COPD. Succinic dehydrogenase activity and sarcoplasmic reticulum (SR) Ca2+-ATPase activity, measured photometrically (OD units), were higher (P < 0.05), and lower (P < 0.05), respectively, in type I compared to the type II fiber subtypes. These properties were not altered with COPD. COPD in females is accompanied by a higher percent of type II fibers, a larger CSA of type I and type IIA fibers, both of which occur in the absence of differences in oxidative potential and the potential for SR Ca2+-sequestration.

Cellular assessment of muscle in COPD: case studies of two males

“…A common and expected response was the large increase in the percentage of the fast-twitch, type II fibers and the decrease in the slow-twitch, type I fiber percent observed in both patients in this study and our earlier study 26. The change in the fiber type profile in COPD which has been observed many times previously2,4 has been attributed to a simple transformation of fiber types 3.…”

“…To contrast the different effects of COPD on muscle, we have selected two COPD patients with advanced COPD disease but differing in the degree of cachexia. Dual energy X-ray (DEXA) to measure body composition26 was applied to confirm differences between COPD #1 and COPD #2 in lean body mass. Our objective was to address both the processes involved in ATP production (metabolic pathways) and the processes involved in ATP utilization with emphasis on cation cycling.…”

“…This work was part of a much larger project investigating skeletal muscle in COPD in which we have published a number of papers dealing with metabolic organization,18 the sarcoplasmic reticulum,5 the Na + -K + -ATPase,6 energetic and transporters status21 and muscle fiber type characteristics 26…”

A pilot study to determine whether differences exist in histochemical properties between the trapezius and extensor carpi radialis brevis muscles in women with work-related myalgia

“…One section was dedicated to the measurement of a range of properties involved in excitation-contraction coupling (Green et al 2008(Green et al , 2011a, while a second sample was used for the assessment of muscle metabolites, glucose and monocarboxylate transporters, and a range of enzymes representative of metabolic pathways and segments specific to the mitochondria and the cytosol (Green et al 2011b). The other sample was used for the measurement of a range of histochemical properties (Green et al 1998(Green et al , 2009). This tissue was oriented under a dissecting microscope, mounted in embedding medium, rapidly frozen in isopentane cooled to the temperature of liquid nitrogen, and stored at -80°C until analysis.…”

“…By using serial sections stained for the different properties, it was possible to correlate the findings to a specific fibre, and to the different fibre types and subtypes. Details for the histochemical measurements have been previously published by our group (Green et al 1998(Green et al , 2009.…”