. Electrolytes in biological systems, incorporating papers presented at a symposium at the Marine Biological Laboratory in Woods Hole, Massachusetts, on September 8, 1954. Electrophysiology; Electrolytes; Electrolytes; Electrophysiology; Physiology, Comparative. 76 ELECTROLYTES IN BIOLOGICAL SYSTEMS associated with the markedly diminished cellular concentration of K+ and perhaps with a drop in cellular pH. At the time of writing, data on K+ leakage are incomplete, but certain con- clusions can be drawn. The leakage of K+ is accompanied by an inflow of H+ from the medium. Both ions are moving w
. Electrolytes in biological systems, incorporating papers presented at a symposium at the Marine Biological Laboratory in Woods Hole, Massachusetts, on September 8, 1954. Electrophysiology; Electrolytes; Electrolytes; Electrophysiology; Physiology, Comparative. 76 ELECTROLYTES IN BIOLOGICAL SYSTEMS associated with the markedly diminished cellular concentration of K+ and perhaps with a drop in cellular pH. At the time of writing, data on K+ leakage are incomplete, but certain con- clusions can be drawn. The leakage of K+ is accompanied by an inflow of H+ from the medium. Both ions are moving with the concentration gradient, which probably supplies the driving force. The leakage rate is very dependent on extracellular pH. There is a minimum leakage at pH with an increased rate up to pn (no data are as yet available above pH ) and down to pH The rates are remarkably high at low values of pH. The metabolizing cell can take up K+ despite the pronounced outward leak- age, because the inward transport system is so effective. It has already been. Fig. 6. K"*" leakage by yeast into a K^-free medium as a function of pH, with and without lucose. pointed out that at pn a steady state exists at 5 X io~* m/1. K+, in which the leakage rate is equal to the rate of inflow. The leakage rate is about 12 mivi/kg hr. of cells. Thus the rate of inflow must be at least 12 mn/kg hr. at this re- markably low concentration of K"*". At higher concentrations of K+ the rate of inflow approaches 360 mM/kg hr. The actual rates of inflow may be even higher, because in addition to correcting for the outflow of K+ measured by leakage into a K+-free medium there may be an additional correction for outflow of K+ associated with a K+-K+ exchange when the medium contains appreciable concentrations of K+. The extent of the latter phenomenon can be determined by isotope studies. The relationship between K+ concentration and K+ inflow appears to follow an asymptotic
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