Muscle: A Three Phase System

Abstract

The partition of sulfate, Ca ++, and Mg ++ across the membrane of the sartorius muscle has been studied, and the effect of various concentrations of these ions in the Ringer solution on the cellular level of Na +, K + and CA-has been determined.The level of the three divalent ions in toad plasma and muscle in vivo ha, been assayed. Muscle was found to contain an almost undetectable amount of inorganic sulfate.Increases in the external level of these ions brought about increases in intracellular content, calculated from the found extraeellular space as determined with radioiodinated serum albumin or inulin. Less of the cell water is available to sulfate than to CI-, and the Mg ++ space is less than the Na + space. An amount of muscle water similar to that found for Li + and I -appears to be available to these divalent ions. Sulfate efflux from the cell was extremely rapid, and it was not found possible to differentiate kinetically between intra-and extracellular material.These results are consistent with the theory of a three phase system, assuming the muscle to consist of an extraceUular phase and two intracellular phases. Mg ++ and Ca ++ are adsorbed onto the ordered phase, and increments in cellular content found on raising the external level are assumed to occur in the free intracellular phase.This p a p e r is d e v o t e d to a study of the partition of sulfate, C a ++, a n d M g ++ b e t w e e n the extracellular a n d intracellular phases. T h e r e

The Effect of Dialysate Magnesium on Plasma and Erythrocyte Magnesium and Potassium Concentrations during Maintenance Haemodialysis

“…A possible inter-relationship between extra-cellular magnesium and intra cellular potassium concentrations has been suggested by in vitro studies [8,9], The results described here indicate that an inter-relationship between plasma magnesium and erythrocyte potassium concentrations is also demonstrable in vivo.…”