EFFECTS OF pH, CALCIUM IONS AND ATP ON RIGOR CONTRACTION IN GLYCERINATED RABBIT PSOAS MUSCLE FIBER

Isometric tension development of glycerinated rabbit skeletal muscle fibers due to rigor contraction in the presence or absence of calcium ions was estimated at varying pHs from 6.2‐9.0. The onset and extent of rigor contraction were faster at alkaline pHs than at acidic pHs. Both of the onset and the extent of rigor contraction became faster and greater respectively as calcium ions in the medium increased from 10 −9 to 10 −5 M. At a constant pH value of 7.0 and in the absence of calcium ions, alteration in ATP concentrations in a relaxing solution from 5.0‐1.0 mM did not influence the magnitude of the tension developed in rigor contraction.