Effect of HCl on transmembrane potentials and intracellular pH in rabbit esophageal epithelium.
OBJECTIVE
Acidification of the basolateral membrane by adding HCl to the serosal solution of esophageal epithelium leads to more necrosis than acidification of the apical membrane by adding HCl to the luminal solution. The aim of this study was to examine the mechanism for this difference.


METHODS
The effect of low extracellular pH (pHo) (HCl) on intracellular pH (pHi) and transmembrane potentials was examined in rabbit esophageal cells by impalement with intracellular microelectrodes.


RESULTS
Lowering luminal pH to 3.0 had no effect on membrane voltage and/or pHi in either luminally or serosally impaled cells, although a decline in both parameters occurred at pH 1.5 in luminally impaled cells. In contrast, lowering serosal pH from 7.4 to 3.0 progressively reduced membrane voltage and/or pHi. Membrane depolarization at low pHo was inhibited by a high-potassium solution or barium and mimicked by lowering pHi (gassing with CO2) at neutral pHo.


CONCLUSIONS
Basolateral, but not apical, membranes of esophageal epithelial cells are highly permeable to H+, accounting for the greater susceptibility to damage from exposure to serosal than luminal acid. Membrane depolarization at low pHo is mediated by low pHi through inhibition of basolateral membrane K+ conductance.
Khalbuss
W E
WE
Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
Marousis
C G
CG
Subramanyam
M
M
Orlando
R C
RC
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004594:Electrophysiology; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D004947:Esophagus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism; D006851:Hydrochloric Acid / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D011817:Rabbits
D006851:Hydrochloric Acid