Contractile properties of muscle fibers from the deep and superficial digital flexors of horses
| Autor: | John E. A. Bertram, John W. Hermanson, A. N. Clark, Nicolas M. Brunet, M. T. Butcher, P.B. Chase |
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| Rok vydání: | 2010 |
| Předmět: |
Male
Physiology Muscle Fibers Skeletal Context (language use) Isometric exercise Myosins Biology Body Temperature Tendons Cell Movement Isometric Contraction Physiology (medical) Myosin medicine Animals Horses Muscle Skeletal Myosin Heavy Chains Extramural Articles Anatomy Cell movement Flexor muscles Immunohistochemistry Biomechanical Phenomena Tendon medicine.anatomical_structure Calcium Electrophoresis Polyacrylamide Gel Female Joints medicine.symptom Locomotion Muscle Contraction Muscle contraction |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 299:R996-R1005 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.00510.2009 |
| Popis: | Equine digital flexor muscles have independent tendons but a nearly identical mechanical relationship to the main joint they act upon. Yet these muscles have remarkable diversity in architecture, ranging from long, unipennate fibers (“short” compartment of DDF) to very short, multipennate fibers (SDF). To investigate the functional relevance of the form of the digital flexor muscles, fiber contractile properties were analyzed in the context of architecture differences and in vivo function during locomotion. Myosin heavy chain (MHC) isoform fiber type was studied, and in vitro motility assays were used to measure actin filament sliding velocity (Vf). Skinned fiber contractile properties [isometric tension (P0/CSA), velocity of unloaded shortening (VUS), and force-Ca2+relationships] at both 10 and 30°C were characterized. Contractile properties were correlated with MHC isoform and their respective Vf. The DDF contained a higher percentage of MHC-2A fibers with myosin (heavy meromyosin) and Vfthat was twofold faster than SDF. At 30°C, P0/CSA was higher for DDF (103.5 ± 8.75 mN/mm2) than SDF fibers (81.8 ± 7.71 mN/mm2). Similarly, VUS(pCa 5, 30°C) was faster for DDF (2.43 ± 0.53 FL/s) than SDF fibers (1.20 ± 0.22 FL/s). Active isometric tension increased with increasing Ca2+concentration, with maximal Ca2+activation at pCa 5 at each temperature in fibers from each muscle. In general, the collective properties of DDF and SDF were consistent with fiber MHC isoform composition, muscle architecture, and the respective functional roles of the two muscles in locomotion. |
| Databáze: | OpenAIRE |
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