Chloride Effect on a Neutral-Carrier-Based pH-Sensitive Microelectrode and Its Intracellular Application
Type: article
Abstract: In order to measure the intracellular pH (pHi), single and double-barreled liquid ionexchanger H+-selective microelectrodes were constructed with a neutral-carrier-based H+ ligand. Average slopes of single and double-barreled microelectrodes were －56.3 ±1.34 mV/pH (SE, n=30) and －52.6 ±0.78 mV/pH (n=65), respectively. These microelectrodes exhibited an abnormal response to excess Cl- in test solutions of pH from 2 to 5: i.e., in the pH range between 4 and 5, super-Nernstian responses of LIX pH-microelectrode occurred, whereas in the range of 2 to 4, sub-Nernstian responses appeared, depending upon the concentration of Cl- ion (but not SO24- or HPO24-) in the calibration solutions. In the practical application, the pHi of in vitro sartorius muscle was 7.05 ±0.021 (n=47), and the membrane potential difference (EM) was －57.3 ±1.62 mV in the medium of pH 7.57. A positive correlation was observed between pHi and EM (r=0.623, P＜0.01). This indicates that the H+ distribution across the membrane is only partly influenced by Donnan force. In contrast, in the proximal tubule in vivo, pHi was 7.22 ±0.013 (n=37); and the peritubular EM was －55. 4 ±2.34 mV. A negative correlation found between pHi and EM (r=－0.483, P＜0.01) suggests that an active H+ pump is operating against the electrochemical gradient for H+ across the cell membrane in the tubule. Thus, the above neutral-carrier pH-microelectrodes are valuable tools for cell pH studies in the physiological range.
Language: English
Subfield: Bioengineering
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7145307367
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