QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online January 31, 2006
Journal of Experimental Biology 209, 668-676 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02033

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend 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 Höpflinger, M. C. Articles by Galler, S. Search for Related Content PubMed PubMed Citation Articles by Höpflinger, M. C. Articles by Galler, S. Social Bookmarking                         What's this?

Effect of pH on the rate of myosin head detachment in molluscan catch muscle: are myosin heads involved in the catch state?

Marion Christine Höpflinger, Olena Andruchova, Oleg Andruchov, Herbert Grassberger and Stefan Galler^*

Department of Cell Biology, University of Salzburg, Hellbrunnerstr. 34, A-5020 Salzburg, Austria

^* Author for correspondence (e-mail: Stefan.Galler{at}sbg.ac.at)

Accepted 13 December 2005

Moderate alkalisation is known to terminate the catch state of bivalve mollusc smooth muscles such as the anterior byssus retractor muscle (ABRM) of Mytilus edulis L. In the present study, we investigated the effect of moderate alkalisation (pH 7.2-7.7 vs control pH 6.7) on the myosin head detachment rate in saponin-skinned fibre bundles of ABRM in order to investigate the possible role of myosin heads in the force maintenance during catch. The detachment rate of myosin heads was deduced from two types of experiments. (1) In stretch experiments on maximally Ca²⁺-activated fibre bundles (pCa 4.5), the rate of force decay after stepwise stretch was assessed. (2) In ATP step experiments, the rate of force decay from high force rigor (pCa>8) was evaluated. The ATP step was induced by photolysis of caged ATP. We found that moderate alkalisation induces relaxation of skinned fibres in catch, thereby reducing both force and stiffness, whereas it does not accelerate the rate of myosin head detachment. This acceleration, however, would be expected if catch would be simply due to myosin heads remaining sustainably attached to actin filaments. Thus, the myosin heads may be less involved in catch than generally assumed. Catch may possibly depend on a different kind of myofilament interconnections, which are abolished by moderate alkalisation.

Key words: catch muscle, mollusc smooth muscle, Mytilus edulis, pH effect, caged ATP

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. Galler, J. Litzlbauer, M. Kross, and H. Grassberger The highly efficient holding function of the mollusc 'catch' muscle is not based on decelerated myosin head cross-bridge cycles Proc R Soc B, November 11, 2009; (2009) rspb.2009.1618v1. [Abstract] [Full Text] [PDF]

				D. Funabara, R. Osawa, M. Ueda, S. Kanoh, D. J. Hartshorne, and S. Watabe Myosin Loop 2 Is Involved in the Formation of a Trimeric Complex of Twitchin, Actin, and Myosin J. Biol. Chem., July 3, 2009; 284(27): 18015 - 18020. [Abstract] [Full Text] [PDF]

				D. Funabara, C. Hamamoto, K. Yamamoto, A. Inoue, M. Ueda, R. Osawa, S. Kanoh, D. J. Hartshorne, S. Suzuki, and S. Watabe Unphosphorylated twitchin forms a complex with actin and myosin that may contribute to tension maintenance in catch J. Exp. Biol., December 15, 2007; 210(24): 4399 - 4410. [Abstract] [Full Text] [PDF]

				O. Andruchov, O. Andruchova, and S. Galler The catch state of mollusc catch muscle is established during activation: experiments on skinned fibre preparations of the anterior byssus retractor muscle of Mytilus edulis L. using the myosin inhibitors orthovanadate and blebbistatin J. Exp. Biol., November 1, 2006; 209(21): 4319 - 4328. [Abstract] [Full Text] [PDF]