|
|
||||||||
1 Muscle Cell Biochemistry Laboratory, School of Biomedical Sciences, Victoria University, Melbourne City, Melbourne 8001; and 2 School of Zoology, Faculty of Science and Technology, La Trobe University, Bundoora, Victoria 3083, Australia
In this study, we investigated whether the previously established differences between fast- and slow-twitch single skeletal muscle fibers of the rat, in terms of myosin heavy chain (MHC) isoform composition and contractile function, are also detectable in excitation-contraction (E-C) coupling. We compared the contractile responsiveness of electrophoretically typed, mechanically skinned single fibers from the soleus (Sol), the extensor digitorum longus (EDL), and the white region of the sternomastoid (SM) muscle to t-system depolarization-induced activation. The quantitative parameters assessed were the amplitude of the maximum depolarization-induced force response (DIFRmax; normalized to the maximum Ca2+-activated force in that fiber) and the number of responses elicited until the force declined by 75% of DIFRmax (R-D75%). The mean DIFRmax values for type IIB EDL and type IIB SM fibers were not statistically different, and both were greater than the mean DIFRmax for type I Sol fibers. The mean R-D75% for type IIB EDL fibers was greater than that for type I Sol fibers as well as type IIB SM fibers. These data suggest that E-C coupling characteristics of mechanically skinned rat single muscle fibers are related to MHC-based fiber type and the muscle of origin.
excitation-contraction coupling; myosin heavy chain; single muscle fiber; hybrid fiber
This article has been cited by other articles:
![]() |
M. F. Patterson, G. M. M. Stephenson, and D. G. Stephenson Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat Am J Physiol Cell Physiol, September 1, 2006; 291(3): 518 - 528. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. O'Connell, R. Blazev, and G. M. M. Stephenson Electrophoretic and functional identification of two troponin C isoforms in toad skeletal muscle fibers Am J Physiol Cell Physiol, February 1, 2006; 290(2): C515 - C523. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. O'Connell, D. G. Stephenson, R. Blazev, and G. M. M. Stephenson Troponin C isoform composition determines differences in Sr2+-activation characteristics between rat diaphragm fibers Am J Physiol Cell Physiol, July 1, 2004; 287(1): C79 - C87. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |