ISSN:
1432-2013
Keywords:
Chloride microelectrode
;
Porphin manganese(III) chloride
;
S3 segment of rabbit renal proximal tubule
;
Intracellular chloride activity
;
Residual chloride
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract 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 HCO 3 − 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 logK Cl, HCO3 pot 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 HCO 3 − 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00582133
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