[Amplitude of the tension developed by glycerinated muscle fibers during rigidity depends on the nature of the structural reorganizations in F-actin induced by formation of the actomyosin complex].

Dependence between the amplitude of tension, developed by glycerinated muscle fibers during rigidity, and the character of structural changes in F-actin, induced by the formation of actomyosin complex, was studied by polarized microfluorimetry and tensiometry. It is shown that during rigidity the anisotropy of intrinsic tryptophan residues as well as of rhodamine phalloidin bound to F-actin, and amplitude of tension depend on pH (6-8) and ionic strength (mu = 0.07 M-0.14 M) of solution. Greater changes in polarized fluorescence and in amplitude of tension were registered during rigidity in solutions with low ionic strength (mu = 0.07 M) and pH 8. It suggested that the amplitude of muscle fibre tension depends on the relative quantity of actin monomers, being in the "switched on" state.