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Journal Article

A new double-barrelled, ionophore-based microelectrode for chloride ions


Frömter,  Eberhard
Department of Physiology, Max Planck Institute of Biophysics, Max Planck Society;
Zentrum der Physiologie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt, Federal Republic of Germany;

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Kondo, Y., Bührer, T., Frömter, E., & Simon, W. (1989). A new double-barrelled, ionophore-based microelectrode for chloride ions. Pflügers Archiv: European Journal of Physiology, 414(6), 663-668. doi:10.1007/BF00582133.

Cite as: https://hdl.handle.net/21.11116/0000-0009-D036-F
A new Cl selective microelectrode based on the ionophore 5,10,15,20-tetraphenyl-21H,23H-porphin manganese(III) chloride is presented which discriminates better against HCO3 and several organic anions than electrodes containing the Corning 477913 ion-eschanger. Using a redesigned construction procedure, fine-tip double-barrelled microelectrodes were produced which had slopes of −52.4±0.6 mV (SE,n=24), resistances of about 7·1011 Ω and a selectivity coefficient log potCl, HCO3 of −1.40±0.03. Some electrodes showed a small unexplained sensitivity to pH>7.6. When used to puncture cells of isolated S3 segments of rabbit renal proximal tubule during perfusion with HCO3 Ringer solution, the electrodes gave a membrane potential of −69.8±1.5 mV and an intracellular Cl activity, [Cl]i, of 35.3±2.6 mmol/l. Upon switching bath and lumen perfusions to Cl-free solutions the “residual” [Cl]i dropped to 1.20±0.03 mmol/l, while in similar measurements with ion-exchanger electrodes the “residual” [Cl]i dropped only to 10.9±0.5 mmol/l. These observations demonstrate the superiority of the new electrode and prove that previously determined high [Cl]i values in Cl-free ambient solutions reflect interference problems rather than non-exchangeable intracellular chloride.