Low doses of ethanol have Ca2+ ionophore-like effects on apical membrane potential of in vitro Necturus antrum

Michael Rutten, C. D. Moore

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The effects of low doses of luminal ethanol on the amiloride-sensitive apical membrane potential of Necturus antral mucosa were studied using conventional microelectrode techniques. Luminal ethanol (0.250-4.0% vol/vol) caused a dose-dependent hyperpolarization of the apical membrane potential (V(mc)), an increase in transepithelial resistance (R(t)) and resistance ratio (R(a)/R(b)), and a decrease in transepithelial potential (V(ms)). Luminal amiloride (100 μM) to 4% ethanol-treated antra did not cause any additional hyperpolarization of V(mc). Compared with luminal 2% ethanol-Ringer, an equivalent osmotic mannitol solution depolarized V(mc) and basolateral potential (V(cs)), decreased R(t) and R(a)/R(b), and increased V(ms). A single dose of 0.50% ethanol attenuated the effects of a second 2% ethanol exposure on V(mc). No change in periodic acid-Schiff (PAS)-positive mucous granule content could be found between control and 2% ethanol-treated antra. The Ca2+ ionophores A23187 or ionomycin (0.25-5.0 μM) dose dependently hyperpolarized the V(mc) and V(cs), increased R(t) and R(a)/R(b), and decreased V(ms). Luminal Ca2+-free Ringer had no effect on luminal 2.00% ethanol-induced changes in membrane potentials or resistances. Pretreatment with BAPTA blocked by ~70 and 55% the V(mc) hyperpolarization of 2 and 4% ethanol, respectively. Pretreatment with ruthenium red (10-50 μM) also dose dependently reduced the 2% ethanol-induced changes in V(mc). The data indicate that 1) low doses of luminal ethanol and Ca2+ ionophores have similar effects on Necturus gastric antral membrane potentials and resistances, 2) ethanol-induced hyperpolarizations of the V(mc) are partially mediated through an alteration in intracellular Ca2+, and 3) low doses of luminal ethanol do not cause the release of antral epithelial mucous granules at the time when significant changes are occurring in the V(mc).

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume261
Issue number1 24-1
StatePublished - 1991
Externally publishedYes

Fingerprint

Necturus
Ionophores
Membrane Potentials
Ethanol
Amiloride
In Vitro Techniques
Ruthenium Red
Ionomycin
Periodic Acid
Calcimycin
Microelectrodes
Mannitol

Keywords

  • 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
  • A23187
  • Amiloride
  • Calcium permeability
  • Gastric antrum
  • Ionomycin
  • Mucus
  • Ruthenium red
  • Sodium permeability

ASJC Scopus subject areas

  • Physiology
  • Gastroenterology

Cite this

@article{98eb1418bcf8430b8f8291c8a4986634,
title = "Low doses of ethanol have Ca2+ ionophore-like effects on apical membrane potential of in vitro Necturus antrum",
abstract = "The effects of low doses of luminal ethanol on the amiloride-sensitive apical membrane potential of Necturus antral mucosa were studied using conventional microelectrode techniques. Luminal ethanol (0.250-4.0{\%} vol/vol) caused a dose-dependent hyperpolarization of the apical membrane potential (V(mc)), an increase in transepithelial resistance (R(t)) and resistance ratio (R(a)/R(b)), and a decrease in transepithelial potential (V(ms)). Luminal amiloride (100 μM) to 4{\%} ethanol-treated antra did not cause any additional hyperpolarization of V(mc). Compared with luminal 2{\%} ethanol-Ringer, an equivalent osmotic mannitol solution depolarized V(mc) and basolateral potential (V(cs)), decreased R(t) and R(a)/R(b), and increased V(ms). A single dose of 0.50{\%} ethanol attenuated the effects of a second 2{\%} ethanol exposure on V(mc). No change in periodic acid-Schiff (PAS)-positive mucous granule content could be found between control and 2{\%} ethanol-treated antra. The Ca2+ ionophores A23187 or ionomycin (0.25-5.0 μM) dose dependently hyperpolarized the V(mc) and V(cs), increased R(t) and R(a)/R(b), and decreased V(ms). Luminal Ca2+-free Ringer had no effect on luminal 2.00{\%} ethanol-induced changes in membrane potentials or resistances. Pretreatment with BAPTA blocked by ~70 and 55{\%} the V(mc) hyperpolarization of 2 and 4{\%} ethanol, respectively. Pretreatment with ruthenium red (10-50 μM) also dose dependently reduced the 2{\%} ethanol-induced changes in V(mc). The data indicate that 1) low doses of luminal ethanol and Ca2+ ionophores have similar effects on Necturus gastric antral membrane potentials and resistances, 2) ethanol-induced hyperpolarizations of the V(mc) are partially mediated through an alteration in intracellular Ca2+, and 3) low doses of luminal ethanol do not cause the release of antral epithelial mucous granules at the time when significant changes are occurring in the V(mc).",
keywords = "1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, A23187, Amiloride, Calcium permeability, Gastric antrum, Ionomycin, Mucus, Ruthenium red, Sodium permeability",
author = "Michael Rutten and Moore, {C. D.}",
year = "1991",
language = "English (US)",
volume = "261",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "1 24-1",

}

TY - JOUR

T1 - Low doses of ethanol have Ca2+ ionophore-like effects on apical membrane potential of in vitro Necturus antrum

AU - Rutten, Michael

AU - Moore, C. D.

PY - 1991

Y1 - 1991

N2 - The effects of low doses of luminal ethanol on the amiloride-sensitive apical membrane potential of Necturus antral mucosa were studied using conventional microelectrode techniques. Luminal ethanol (0.250-4.0% vol/vol) caused a dose-dependent hyperpolarization of the apical membrane potential (V(mc)), an increase in transepithelial resistance (R(t)) and resistance ratio (R(a)/R(b)), and a decrease in transepithelial potential (V(ms)). Luminal amiloride (100 μM) to 4% ethanol-treated antra did not cause any additional hyperpolarization of V(mc). Compared with luminal 2% ethanol-Ringer, an equivalent osmotic mannitol solution depolarized V(mc) and basolateral potential (V(cs)), decreased R(t) and R(a)/R(b), and increased V(ms). A single dose of 0.50% ethanol attenuated the effects of a second 2% ethanol exposure on V(mc). No change in periodic acid-Schiff (PAS)-positive mucous granule content could be found between control and 2% ethanol-treated antra. The Ca2+ ionophores A23187 or ionomycin (0.25-5.0 μM) dose dependently hyperpolarized the V(mc) and V(cs), increased R(t) and R(a)/R(b), and decreased V(ms). Luminal Ca2+-free Ringer had no effect on luminal 2.00% ethanol-induced changes in membrane potentials or resistances. Pretreatment with BAPTA blocked by ~70 and 55% the V(mc) hyperpolarization of 2 and 4% ethanol, respectively. Pretreatment with ruthenium red (10-50 μM) also dose dependently reduced the 2% ethanol-induced changes in V(mc). The data indicate that 1) low doses of luminal ethanol and Ca2+ ionophores have similar effects on Necturus gastric antral membrane potentials and resistances, 2) ethanol-induced hyperpolarizations of the V(mc) are partially mediated through an alteration in intracellular Ca2+, and 3) low doses of luminal ethanol do not cause the release of antral epithelial mucous granules at the time when significant changes are occurring in the V(mc).

AB - The effects of low doses of luminal ethanol on the amiloride-sensitive apical membrane potential of Necturus antral mucosa were studied using conventional microelectrode techniques. Luminal ethanol (0.250-4.0% vol/vol) caused a dose-dependent hyperpolarization of the apical membrane potential (V(mc)), an increase in transepithelial resistance (R(t)) and resistance ratio (R(a)/R(b)), and a decrease in transepithelial potential (V(ms)). Luminal amiloride (100 μM) to 4% ethanol-treated antra did not cause any additional hyperpolarization of V(mc). Compared with luminal 2% ethanol-Ringer, an equivalent osmotic mannitol solution depolarized V(mc) and basolateral potential (V(cs)), decreased R(t) and R(a)/R(b), and increased V(ms). A single dose of 0.50% ethanol attenuated the effects of a second 2% ethanol exposure on V(mc). No change in periodic acid-Schiff (PAS)-positive mucous granule content could be found between control and 2% ethanol-treated antra. The Ca2+ ionophores A23187 or ionomycin (0.25-5.0 μM) dose dependently hyperpolarized the V(mc) and V(cs), increased R(t) and R(a)/R(b), and decreased V(ms). Luminal Ca2+-free Ringer had no effect on luminal 2.00% ethanol-induced changes in membrane potentials or resistances. Pretreatment with BAPTA blocked by ~70 and 55% the V(mc) hyperpolarization of 2 and 4% ethanol, respectively. Pretreatment with ruthenium red (10-50 μM) also dose dependently reduced the 2% ethanol-induced changes in V(mc). The data indicate that 1) low doses of luminal ethanol and Ca2+ ionophores have similar effects on Necturus gastric antral membrane potentials and resistances, 2) ethanol-induced hyperpolarizations of the V(mc) are partially mediated through an alteration in intracellular Ca2+, and 3) low doses of luminal ethanol do not cause the release of antral epithelial mucous granules at the time when significant changes are occurring in the V(mc).

KW - 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid

KW - A23187

KW - Amiloride

KW - Calcium permeability

KW - Gastric antrum

KW - Ionomycin

KW - Mucus

KW - Ruthenium red

KW - Sodium permeability

UR - http://www.scopus.com/inward/record.url?scp=0025860723&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025860723&partnerID=8YFLogxK

M3 - Article

C2 - 1713418

AN - SCOPUS:0025860723

VL - 261

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 1 24-1

ER -