PMID: 42004Jan 1, 1979

The measurement of intracellular sodium activities in the bullfrog by means of double-barreled sodium liquid ion-exchanger microelectrodes

Membrane Biochemistry
K KoteraM Fujimoto


A double-barreled Na+-selective microelectrode was constructed with monensin as a liquid ion exchanger. The HCl-treated monensin was dissolved in a solvent (Corning 477317) at 10% (weight/weight). Internal reference solution of its ionic barrel was mixture of 0.49 M NaCl and 0.01 M KCl, the pH being adjusted to 3 with 0.1 M citrate-HCl buffer, whereas that of the PD barrel was 0.5 M KCl. Average slope and selectivity ratio (Na+/K+) tested on 10 different microelectrodes were -57.5 +/- 1.87 mV/P(Na) (SEM) and 6.7 +/- 0.44, respectively. The electrical resistance was an order of 10(10) ohm and the response time was less than 10 sec. Using this microelectrode, a free flow micropuncture experiment was carried out in the bullfrog kidney and the intracellular Na+ activity as well as the membrane PD was determined on the proximal tubular cell. Average value (+/- SEM, n = 15) for the intracellular Na+ and K+ was 20.7 +/- 1.56 mEq/L and 61.2 +/- 1.16 mEq/L, respectively, and -68.7 +/- 0.88 mV for the peritubular membrane PD. There was a significant negative correlation between Na+ and K+ activities within the cell, i.e., the lower the ionic activity of cellular Na+ was, the higher the cellular K+, and vice versa, the sum of these two be...Continue Reading


Dec 15, 1978·Pflügers Archiv : European journal of physiology·A EdelmanE Frömter
May 6, 1977·The Journal of Membrane Biology·L G Palmer, M M Civan
Sep 1, 1976·The Journal of General Physiology·H M Brown
Jan 1, 1972·The Journal of Physiology·R C Thomas


Jan 1, 1984·The Journal of Membrane Biology·J W Hanrahan, J E Phillips
Jun 24, 1985·Neuroscience Letters·D Ammann, P Anker

Related Concepts

Hydrogen-Ion Concentration
Intracellular Fluid
Ion Exchange
Kidney Tubules, Proximal
Resting Potentials
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