Biophysical Journal 70: 2333-2340 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Patel, J R Articles by Moss, R L Search for Related Content PubMed PubMed Citation Articles by Patel, J R Articles by Moss, R L

Myosin regulatory light chain modulates the Ca2+ dependence of the kinetics of tension development in skeletal muscle fibers.

Department of Physiology, University of Wisconsin, Madison 53706, USA.

ABSTRACT

To determine the role of myosin regulatory light chain (RLC) in modulating contraction in skeletal muscle, we examined the rate of tension development in bundles of skinned skeletal muscle fibers as a function of the level of Ca(2+) activation after UV flash-induced release of Ca(2+) from the photosensitive Ca(2+) chelator DM-nitrophen. In control fiber bundles, the rate of tension development was highly dependent on the concentration of activator Ca(2+) after the flash. There was a greater than twofold increase in the rate of tension development when the post-flash [Ca(2+)] was increased from the lowest level tested (which produced a steady tension that was 42% of maximum tension) to the highest level (producing 97% of maximum tension). However, when 40-70% of endogenous myosin RLC was extracted from the fiber bundles, tension developed at the maximum rate, regardless of the post-flash concentration of Ca(2+). Thus, the Ca(2+) dependence of the rate of tension development was eliminated by partial extraction of myosin RLC, an effect that was partially reversed by recombination of RLC back into the fiber bundles. The elimination of the Ca(2+) dependence of the kinetics of tension development was specific to the extraction of RLC rather than an artifact of the co-extraction of both RLC and Troponin C, because the rate of tension development was still Ca(2+) dependent, even when nearly 50% of endogenous Troponin C was extracted from fiber bundles fully replete with RLC. Thus, myosin RLC appears to be a key component in modulating Ca(2+) sensitive cross-bridge transitions that limit the rate of force development after photorelease of Ca(2+) in skeletal muscle fibers.

This article has been cited by other articles:

				J. E. Stelzer, J. R. Patel, and R. L. Moss Acceleration of Stretch Activation in Murine Myocardium due to Phosphorylation of Myosin Regulatory Light Chain J. Gen. Physiol., August 28, 2006; 128(3): 261 - 272. [Abstract] [Full Text] [PDF]

				C. Tesi, N. Piroddi, F. Colomo, and C. Poggesi Relaxation Kinetics Following Sudden Ca2+ Reduction in Single Myofibrils from Skeletal Muscle Biophys. J., October 1, 2002; 83(4): 2142 - 2151. [Abstract] [Full Text] [PDF]

				G. C. Sieck and M. Regnier Plasticity in Skeletal, Cardiac, and Smooth Muscle: Invited Review: Plasticity and energetic demands of contraction in skeletal and cardiac muscle J Appl Physiol, March 1, 2001; 90(3): 1158 - 1164. [Abstract] [Full Text] [PDF]

				S. P. Harris, J. R. Patel, L. J. Marton, and R. L. Moss Polyamines decrease Ca2+ sensitivity of tension and increase rates of activation in skinned cardiac myocytes Am J Physiol Heart Circ Physiol, September 1, 2000; 279(3): H1383 - H1391. [Abstract] [Full Text] [PDF]

				A. M. Gordon, E. Homsher, and M. Regnier Regulation of Contraction in Striated Muscle Physiol Rev, April 1, 2000; 80(2): 853 - 924. [Abstract] [Full Text] [PDF]

				A. Sanbe, J. G. Fewell, J. Gulick, H. Osinska, J. Lorenz, D. G. Hall, L. A. Murray, T. R. Kimball, S. A. Witt, and J. Robbins Abnormal Cardiac Structure and Function in Mice Expressing Nonphosphorylatable Cardiac Regulatory Myosin Light Chain 2 J. Biol. Chem., July 23, 1999; 274(30): 21085 - 21094. [Abstract] [Full Text] [PDF]

				D. P. Fitzsimons, J. R. Patel, and R. L. Moss Aging-dependent depression in the kinetics of force development in rat skinned myocardium Am J Physiol Heart Circ Physiol, May 1, 1999; 276(5): H1511 - H1519. [Abstract] [Full Text] [PDF]

				A. J. Baker, V. M. Figueredo, E. C. Keung, and S. A. Camacho Ca2+ regulates the kinetics of tension development in intact cardiac muscle Am J Physiol Heart Circ Physiol, September 1, 1998; 275(3): H744 - H750. [Abstract] [Full Text] [PDF]

				A. Malhotra, D. Reich, D. Reich, A. Nakouzi, V. Sanghi, D. L. Geenen, and P. M. Buttrick Experimental Diabetes Is Associated With Functional Activation of Protein Kinase C{epsilon} and Phosphorylation of Troponin I in the Heart, Which Are Prevented by Angiotensin II Receptor Blockade Circ. Res., December 19, 1997; 81(6): 1027 - 1033. [Abstract] [Full Text]

				D. Szczesna, J. Zhao, M. Jones, G. Zhi, J. Stull, and J. D. Potter Phosphorylation of the regulatory light chains of myosin affects Ca2+ sensitivity of skeletal muscle contraction J Appl Physiol, April 1, 2002; 92(4): 1661 - 1670. [Abstract] [Full Text] [PDF]