Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH

Pierre Dagher, Thomas Behm, Angela Taglietta-Kohlbrecher, Richard W. Egnor, Alan N. Charney

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Intracellular acidification by stimuli other than CO2 fails to stimulate colonic apical Na/H exchange and Na absorption. We examined whether Na absorption could be stimulated in the absence of changes in cytoplasmic pH (pH(i)). Distal colon of male Sprague-Dawley rats was used for pH(i) measurements with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein and for flux measurements in Ussing chambers. In 21 mM HCO3-Ringer, increasing PCO2 from 20 to 70 mmHg decreased pH(i) from 7.51 to 7.03 and increased net Na flux (J(net)/(Na)) from 4.2 ± 0.4 to 6.8 ± 0.6 μeq · cm-2 · h-1. Similar increases in J(net)/(Na) occurred in the absence of mucosal Cl and in the presence of phalloidin to inhibit microfilaments or benzolamide to inhibit membrane-bound carbonic anhydrase. Isohydric increases in PCO2 did not alter pH(i) but stimulated J(net)/(Na) from 5.1 ± 0.6 to 7.2 ± 0.8 μeq · cm-2 · h-1. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) decreased pH(i) from 7.45 to 7.35 but did not stimulate J(net)/(Na). Butyrate (25 mM) decreased pH(i) from 7.15 to 7.02 with recovery to baseline within 6 min; however, J(net)/(Na) increased by 2.2 μeq · cm-2 · h-1 for 60 min. We conclude that apical Na/H exchange activity is unresponsive to changes in bulk pH(i) and is independent of Cl-/HCO3 exchange, microfilaments, and membrane-bound carbonic anhydrase. The presence of an H-tight, CO2, and butyrate-permeable subapical domain is postulated.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume270
Issue number6 39-6
StatePublished - Jun 1996
Externally publishedYes

Fingerprint

Carbonic Anhydrases
Butyrates
Benzolamide
Ion exchange
Thermodynamic properties
Fluxes
Membranes
Phalloidine
Acidification
Rats
Recovery
Actin Cytoskeleton
Sprague Dawley Rats
Colon
2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein
mesoxalonitrile

Keywords

  • 2',7'-bis(carboxyethyl)-5(6)- carboxyfluorescein
  • carbonic anhydrase
  • intracellular pH
  • sodium absorption
  • Sprague-Dawley rat

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

Cite this

Dagher, P., Behm, T., Taglietta-Kohlbrecher, A., Egnor, R. W., & Charney, A. N. (1996). Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH. American Journal of Physiology - Cell Physiology, 270(6 39-6).

Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH. / Dagher, Pierre; Behm, Thomas; Taglietta-Kohlbrecher, Angela; Egnor, Richard W.; Charney, Alan N.

In: American Journal of Physiology - Cell Physiology, Vol. 270, No. 6 39-6, 06.1996.

Research output: Contribution to journalArticle

Dagher, P, Behm, T, Taglietta-Kohlbrecher, A, Egnor, RW & Charney, AN 1996, 'Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH', American Journal of Physiology - Cell Physiology, vol. 270, no. 6 39-6.
Dagher, Pierre ; Behm, Thomas ; Taglietta-Kohlbrecher, Angela ; Egnor, Richard W. ; Charney, Alan N. / Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH. In: American Journal of Physiology - Cell Physiology. 1996 ; Vol. 270, No. 6 39-6.
@article{6d0f1068f6624e628a5c51b5bef7fb88,
title = "Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH",
abstract = "Intracellular acidification by stimuli other than CO2 fails to stimulate colonic apical Na/H exchange and Na absorption. We examined whether Na absorption could be stimulated in the absence of changes in cytoplasmic pH (pH(i)). Distal colon of male Sprague-Dawley rats was used for pH(i) measurements with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein and for flux measurements in Ussing chambers. In 21 mM HCO3-Ringer, increasing PCO2 from 20 to 70 mmHg decreased pH(i) from 7.51 to 7.03 and increased net Na flux (J(net)/(Na)) from 4.2 ± 0.4 to 6.8 ± 0.6 μeq · cm-2 · h-1. Similar increases in J(net)/(Na) occurred in the absence of mucosal Cl and in the presence of phalloidin to inhibit microfilaments or benzolamide to inhibit membrane-bound carbonic anhydrase. Isohydric increases in PCO2 did not alter pH(i) but stimulated J(net)/(Na) from 5.1 ± 0.6 to 7.2 ± 0.8 μeq · cm-2 · h-1. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) decreased pH(i) from 7.45 to 7.35 but did not stimulate J(net)/(Na). Butyrate (25 mM) decreased pH(i) from 7.15 to 7.02 with recovery to baseline within 6 min; however, J(net)/(Na) increased by 2.2 μeq · cm-2 · h-1 for 60 min. We conclude that apical Na/H exchange activity is unresponsive to changes in bulk pH(i) and is independent of Cl-/HCO3 exchange, microfilaments, and membrane-bound carbonic anhydrase. The presence of an H-tight, CO2, and butyrate-permeable subapical domain is postulated.",
keywords = "2',7'-bis(carboxyethyl)-5(6)- carboxyfluorescein, carbonic anhydrase, intracellular pH, sodium absorption, Sprague-Dawley rat",
author = "Pierre Dagher and Thomas Behm and Angela Taglietta-Kohlbrecher and Egnor, {Richard W.} and Charney, {Alan N.}",
year = "1996",
month = "6",
language = "English (US)",
volume = "270",
journal = "American Journal of Physiology",
issn = "0193-1857",
publisher = "American Physiological Society",
number = "6 39-6",

}

TY - JOUR

T1 - Dissociation of colonic apical Na/H exchange activity from bulk cytoplasmic pH

AU - Dagher, Pierre

AU - Behm, Thomas

AU - Taglietta-Kohlbrecher, Angela

AU - Egnor, Richard W.

AU - Charney, Alan N.

PY - 1996/6

Y1 - 1996/6

N2 - Intracellular acidification by stimuli other than CO2 fails to stimulate colonic apical Na/H exchange and Na absorption. We examined whether Na absorption could be stimulated in the absence of changes in cytoplasmic pH (pH(i)). Distal colon of male Sprague-Dawley rats was used for pH(i) measurements with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein and for flux measurements in Ussing chambers. In 21 mM HCO3-Ringer, increasing PCO2 from 20 to 70 mmHg decreased pH(i) from 7.51 to 7.03 and increased net Na flux (J(net)/(Na)) from 4.2 ± 0.4 to 6.8 ± 0.6 μeq · cm-2 · h-1. Similar increases in J(net)/(Na) occurred in the absence of mucosal Cl and in the presence of phalloidin to inhibit microfilaments or benzolamide to inhibit membrane-bound carbonic anhydrase. Isohydric increases in PCO2 did not alter pH(i) but stimulated J(net)/(Na) from 5.1 ± 0.6 to 7.2 ± 0.8 μeq · cm-2 · h-1. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) decreased pH(i) from 7.45 to 7.35 but did not stimulate J(net)/(Na). Butyrate (25 mM) decreased pH(i) from 7.15 to 7.02 with recovery to baseline within 6 min; however, J(net)/(Na) increased by 2.2 μeq · cm-2 · h-1 for 60 min. We conclude that apical Na/H exchange activity is unresponsive to changes in bulk pH(i) and is independent of Cl-/HCO3 exchange, microfilaments, and membrane-bound carbonic anhydrase. The presence of an H-tight, CO2, and butyrate-permeable subapical domain is postulated.

AB - Intracellular acidification by stimuli other than CO2 fails to stimulate colonic apical Na/H exchange and Na absorption. We examined whether Na absorption could be stimulated in the absence of changes in cytoplasmic pH (pH(i)). Distal colon of male Sprague-Dawley rats was used for pH(i) measurements with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein and for flux measurements in Ussing chambers. In 21 mM HCO3-Ringer, increasing PCO2 from 20 to 70 mmHg decreased pH(i) from 7.51 to 7.03 and increased net Na flux (J(net)/(Na)) from 4.2 ± 0.4 to 6.8 ± 0.6 μeq · cm-2 · h-1. Similar increases in J(net)/(Na) occurred in the absence of mucosal Cl and in the presence of phalloidin to inhibit microfilaments or benzolamide to inhibit membrane-bound carbonic anhydrase. Isohydric increases in PCO2 did not alter pH(i) but stimulated J(net)/(Na) from 5.1 ± 0.6 to 7.2 ± 0.8 μeq · cm-2 · h-1. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) decreased pH(i) from 7.45 to 7.35 but did not stimulate J(net)/(Na). Butyrate (25 mM) decreased pH(i) from 7.15 to 7.02 with recovery to baseline within 6 min; however, J(net)/(Na) increased by 2.2 μeq · cm-2 · h-1 for 60 min. We conclude that apical Na/H exchange activity is unresponsive to changes in bulk pH(i) and is independent of Cl-/HCO3 exchange, microfilaments, and membrane-bound carbonic anhydrase. The presence of an H-tight, CO2, and butyrate-permeable subapical domain is postulated.

KW - 2',7'-bis(carboxyethyl)-5(6)- carboxyfluorescein

KW - carbonic anhydrase

KW - intracellular pH

KW - sodium absorption

KW - Sprague-Dawley rat

UR - http://www.scopus.com/inward/record.url?scp=0029746678&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029746678&partnerID=8YFLogxK

M3 - Article

C2 - 8764164

AN - SCOPUS:0029746678

VL - 270

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0193-1857

IS - 6 39-6

ER -