Outflux of Inorganic and Organic Phosphate during Membrane Depolarization of Excitable Tissues

Abstract

IT was reported in a previous paper¹ that the outflux of phosphorus-32 from an isolated sartorius muscle of the frog into phosphate-free Ringer solution was accelerated markedly during electrical stimulation, or when the external solution was devoid of calcium or contained a high potassium (30 mM) concentration. Subsequent findings revealed that not only inorganic phosphate but also many organophosphates such as adenosine triphosphate (ATP) and phosphocreatine were released during membrane depolarization under such experimental conditions. The present communication concerns the outflux of nucleotides and other phosphates from frog sartorius muscle and spinal nerve roots during electrical stimulation and calcium depletion.