Unloaded Speed of Shortening in Voltage-Clamped Intact Skeletal Muscle Fibers from wt, mdx, and Transgenic Minidystrophin Mice Using a Novel High-Speed Acquisition System

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Unloaded Speed of Shortening in Voltage-Clamped Intact Skeletal Muscle Fibers from wt, mdx, and Transgenic Minidystrophin Mice Using a Novel High-Speed Acquisition System

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dc.contributor.author Friedrich, O. en_US
dc.contributor.author Weber, C. en_US
dc.contributor.author Wegner, F. V. en_US
dc.contributor.author Chamberlain, Jeffrey S. en_US
dc.contributor.author Fink, R. H. A. en_US
dc.date.accessioned 2010-04-21T15:48:47Z
dc.date.available 2010-04-21T15:48:47Z
dc.date.issued 2008 en_US
dc.identifier.citation Friedrich O, Weber C, Wegner F, Chamberlain J, Fink R. Unloaded Speed of Shortening in Voltage-Clamped Intact Skeletal Muscle Fibers from wt, mdx, and Transgenic Minidystrophin Mice Using a Novel High-Speed Acquisition System. Biophysical Journal. 2008;94(12):4751-4765. en_US
dc.identifier.other 10.1529/biophysj.107.1265 en_US
dc.identifier.uri http://www.cell.com/biophysj/fulltext/S0006-3495(08)70342-4 en_US
dc.identifier.uri http://hdl.handle.net/1773/15718
dc.description.abstract Skeletal muscle unloaded shortening has been indirectly determined in the past. Here, we present a novel high-speed optical tracking technique that allows recording of unloaded shortening in single intact, voltage-clamped mammalian skeletal muscle fibers with 2-ms time resolution. L-type Ca[super]2+ currents were simultaneously recorded. The time course of shortening was biexponential: a fast initial phase, [Tau]1, and a slower successive phase, [Tau]2, with activation energies of 59 kJ/mol and 47 kJ/mol. Maximum unloaded shortening speed, v[sub]u,max, was faster than that derived using other techniques, e.g.,[approx]14.0 L[sub]0[/sub]s[super]-1 at 30[degrees]C. Our technique also allowed direct determination of shortening acceleration. We applied our technique to single fibers from C57 wild-type, dystrophic mdx, and minidystrophin-expressing mice to test whether unloaded shortening was affected in the pathophysiological mechanism of Duchenne muscular dystrophy. v[sub]u,max and a[sub]u,max values were not significantly different in the three strains, whereas [Tau]1 and [Tau]2 were increased in mdx fibers. The results were complemented by myosin heavy and light chain (MLC) determinations that showed the same myosin heavy chain IIA profiles in the interossei muscles from the different strains. In mdx muscle, MLC-1f was significantly increased and MLC-2f and MLC-3f somewhat reduced. Fast initial active shortening seems almost unaffected in mdx muscle. en_US
dc.description.sponsorship en_US
dc.language.iso en_US en_US
dc.title Unloaded Speed of Shortening in Voltage-Clamped Intact Skeletal Muscle Fibers from wt, mdx, and Transgenic Minidystrophin Mice Using a Novel High-Speed Acquisition System en_US
dc.type Article en_US


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