Measurements of intracellular pH in Necturus antral mucosa by microelectrode technique

S. W. Ashley, D. I. Soybel, L. Y. Cheung

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Abstract

Intracellular pH (pH(i)) was measured in the surface epithelial cells of Necturus antrum using pH-sensitive intracellular microelectrodes. Electrodes were prepared by filling 10- to 20MΩ resistance glass microelectrodes with a H+ ion-selective exchange resin and calibrated before use in solutions of known pH 4.0-8.0. The electrode response (n = 15) was linear ( r = 0.93; P < 0.001) with a slope of 52.1 ± 2.3 mV/pH unit. Antral mucosa was mounted in a modified Ussing chamber and pH(i) was determined from the difference between the potentials recorded by intracellular H+-selective and conventional microelectrodes. These measurements of pH(i) were validated by examining the response of the intracellular microelectrodes to 1) depolarization of the cell membrane produced by K+ substitution for Na+, and 2) alkalinization and acidification of pH(i) produced by NH+4 substitution for Na+ in the bathing solutions. In tissues bathed with HCO-3-Ringer solution (pH 7.0), the mean pH(i) was 7.34 ± 0.02 with a range from 7.24 to 7.43. In N-2-hydroxymethylpiperazine-N'-ethanesulfonic acid (HEPES)-Ringer solution (pH 7.0), pH(i) was reduced to 7.02 ± 0.05 (P < 0.01). Acidification of the luminal solution to pH 6.8 with CO2 produced a 0.22 ± 0.04 pH unit fall in pH(i) (P < 0.001). In contrast, acidification to pH 4.0 with HCl had no significant effects on pH(i). These findings indicate that HCO-3 may play an important role in pH(i) regulation in this tissue. In addition, they suggest that, in contrast to CO2, the surface epithelial cells of Necturus antrum are relatively resistant to acidification by luminal HCl.

Original languageEnglish (US)
Pages (from-to)G625-G632
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume250
Issue number5 (13/5)
DOIs
StatePublished - Jan 1 1986

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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