Journal of applied physiology (1985), 2003-06, Vol.94 (6), p.2188-2196
2003
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- Autor(en) / Beteiligte
- Titel
- ATP consumption rate per cross bridge depends on myosin heavy chain isoform
- Ist Teil von
- Journal of applied physiology (1985), 2003-06, Vol.94 (6), p.2188-2196
- Ort / Verlag
- Bethesda, MD: Am Physiological Soc
- Erscheinungsjahr
- 2003
- Quelle
- MEDLINE
- Beschreibungen/Notizen
- Departments of 1 Anesthesiology and 2 Physiology and Biophysics, Mayo Medical School, Rochester, Minnesota 55905 In the present study, we tested the hypothesis that intrinsic differences in ATP consumption rate per cross bridge exist across rat diaphragm muscle (Dia m ) fibers expressing different myosin heavy chain (MHC) isoforms. During maximum Ca 2+ activation (pCa 4.0) of single, Triton X-permeabilized Dia m fibers, isometric ATP consumption rate was determined by using an NADH-linked fluorometric technique. The MHC concentration in single Dia m fibers was determined by densitometric analysis of SDS-PAGE gels and comparison to a standard curve of known MHC concentrations. Isometric ATP consumption rate varied across Dia m fibers expressing different MHC isoforms, being highest in fibers expressing MHC 2X (1.14 ± 0.08 nmol · mm 3 · s 1 ) and/or MHC 2B (1.33 ± 0.08 nmol · mm 3 · s 1 ), followed by fibers expressing MHC 2A (0.77 ± 0.11 nmol · mm 3 · s 1 ) and MHC Slow (0.46 ± 0.03 nmol · mm 3 · s 1 ). These differences in ATP consumption rate also persisted when it was normalized for MHC concentration in single Dia m fibers. Normalized ATP consumption rate for MHC concentration varied across Dia m fibers expressing different MHC isoforms, being highest in fibers expressing MHC 2X (2.02 ± 0.19 s 1 ) and/or MHC 2B (2.64 ± 0.15 s 1 ), followed by fibers expressing MHC 2A (1.57 ± 0.16 s 1 ) and MHC Slow (0.77 ± 0.05 s 1 ). On the basis of these results, we conclude that there are intrinsic differences in ATP consumption rate per cross bridge in Dia m fibers expressing MHC isoforms. skeletal muscle fibers; energetics; tension cost
- Sprache
- Englisch
- Identifikatoren
- ISSN: 8750-7587eISSN: 1522-1601DOI: 10.1152/japplphysiol.00618.2002Titel-ID: cdi_crossref_primary_10_1152_japplphysiol_00618_2002
- Format
- –
- Schlagworte
- Adenosine Triphosphate - metabolism, Animals, Biological and medical sciences, Diaphragm - metabolism, Energy Metabolism, Fibers, Fundamental and applied biological sciences. Psychology, Hypotheses, Isometric Contraction - physiology, Male, Muscle Fibers, Skeletal - metabolism, Muscle, Skeletal - metabolism, Muscular system, Myosin Heavy Chains - metabolism, Osmolar Concentration, Protein Isoforms - metabolism, Rats, Rats, Sprague-Dawley, Rodents, Striated muscle. Tendons, Tension, Vertebrates: osteoarticular system, musculoskeletal system