PROLONGED SARCOTUBULAR REGENERATIVE RESPONSE IN FROG SARTORIUS MUSCLE

Abstract

The sarcotubular system of frog sartorius muscle fibers generated a prolonged depolarizing regenerative response under appropriate experimental conditions. It was shown from a point-voltage clamp analysis that the inward current component responsible for the response lasts on depolarization for hundreds of milliseconds and reversed its sign when an equilibrium potential was exceeded. The sarcotubular response occurred in F-Ringer solution and was enhanced with EDTA. The response also occurred in normal or propionate-Ringer solution containing EDTA, without great change in the equilibrium potential. The response was inhibited reversibly by picrotoxin. Partial replacement of Na by K in the propionate-Ringer solution reduced the inward current component which suggests that Na may be the responsible ion.