title: Rigor tension development in glycerinated rabbit psoas fibers at high salt concentrations.
abstract: We attempted to measure the rigor tension development by glycerinated fibers of rabbit psoas at high salt concentrations such as 0.5 M KCl. The measurements were made feasible by covalently crosslinking the rod-portion of thick filaments in the fibers in the rigor state with a water-soluble carbodiimide (EDC) so that the thick filaments are not dissolved even at 0.5 M KCl. EDC crosslinks, though with much a slower rate, the myosin cross-bridge heads to the thin filaments. At high salt concentrations, the fibers developed no active tension but developed rigor tension when they were put into a rigor solution from a contracting or relaxing solution. Removal of only Mg++ from a MgATP-containing solution induced similar rigor tension development. The magnitude of the rigor tension was proportional to the fraction of the cross-bridge heads that were crosslinked to the thin filaments. The results suggest that the rigor tension at high salt concentrations is generated by structural changes in the cross-bridge heads that are crosslinked to the thin filaments, when these heads release MgATP or Mg++ (with ATP retained) from their active sites, but not generated by re-formation of the rigor complexes of uncrosslinked myosin heads with the thin filaments. Extrapolation to 100% crosslinked heads gave an estimate of the rigor tension development of more than 1 kg wt/cm2 at high salt concentrations.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tawada
authors.forename: Y
authors.initials: Y
authors.lastname: Emoto
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D000818:Animals; D005990:Glycerol; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D011189:Potassium Chloride; D005990:Glycerol