STUDY OF THE INTRACELLULARLY FREE MOVEMENTS OF IONS IN FROG SARTORIUS MUSCLE FIBERS

Abstract

Ionic movements across the cell membrane are supposed to be governed by respective hypothetical driving forces although there is a possibility of protoplasmic flow without any definite direction in muscle fibers. The existence of intracellularly free ion movements has been assumed from the data on exchangeability of labeled ions across the membrane. Roughly speaking, it has been said that almost all the K ions and about half of the Na ions can move freely in the cells. But details of ionic behavior remain obscure.There has been some uncertainty as to what fraction of the total ion content may be ascribed to the intracellular compartment. It is the purpose of this report to discuss what amount of ions in cells is freely present and how they behave. The state of ionization within cells was evaluated by observing the easiness of intracellular ion movements and the balance sheets for K and Na ions of muscles under various experimental conditions. In other words, the purpose of this report is to discuss the mechanism which maintains internal ionic homeostasis.