MODE OF ACTION OF PRILOCAINE ON SARCOPLASMIC-RETICULUM IN SKINNED SKELETAL-MUSCLE FIBERS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 219  (3) , 815-820
Abstract
Single fibers were isolated from the semitendinosus muscle of a frog, and the skinned fibers were prepared by the removal of the sarcolemma. In the range of several millimolar concentrations, prilocaine, a local anesthetic, caused a contracture of the single fibers in polarized and depolarized states. It also induced Ca2+ release from the sarcoplasmic reticulum [Sl/) and depressed CaI+ uptake by the SR. Prilocaine increased the release of Ca2+ with increasing concentration, but, unlike caffeine, prilocaine could not enhance the Ca2+-induced Ca2+ release mechanism of the SR. Like a depolarization-induced Ca2+ release, the prilocaine-induced Ca2+ release was not inhibited by Mg2+; it was inhibited by sucrose. The Ca2+ release induced with prilocaine occurred only immediately after the application; thereafter, the Ca2+ release mechanism seemed to be inactivated by the prolonged presence of the drug. A similar inactivation in the mechanism of prilocaine-induced Ca2+ release also occurred when the extent of depolarization of the SR membrane increased. The mode of action of prilocaine on the SR could be a depolarization-like action.