Mechanisms of regulatory volume decrease in nonpigmented human ciliary epithelial cells

J. S. Adorante, Peter M Cala

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

To study the net solute and water efflux pathways of the ciliary epithelium we employed a cultured human NPE cell line. Because of the possible relationship between transepithelial ion and water flux and cell volume regulation, the ion efflux pathways mediating regulatory volume decrease (RVD) were investigated. Osmotic swelling of NPE cells was followed by a volume recovery. Volume recovery was K+ dependent and inhibited by K+ channel blockers such as quinine (1 mM). After osmotic swelling, a Cl-- dependent membrane depolarization occurred that was inhibited by Cl- channel blockers such as 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 μM) or Ca2+ chelators such as ethylene glycolbis(β-aminoethyl ether)-N,N,N',N'- tetraacetic acid (EGTA, 2.0 mM). Cell swelling was also accompanied by an increase in intracellular Ca2+ concentration ([Ca2+](i)) of ~200 nM. The swelling-induced rise in [Ca2+](i) and RVD were diminished in the presence of 10 μM La3+, 50 nM 12-O-tetradecanoylphorbol 13-acetate, and nominally Ca2+-free medium. Near total blockage of RVD occurred after pretreatment of NPE cells with Ca2+-free EGTA-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA) acetoxymethyl ester-containing solutions. The inhibition of RVD by EGTA-BAPTA treatment was overcome by increasing K+ conductance with gramicidin. The above findings indicate that RVD in NPE cells is mediated by separate K+ and Cl- conductances (channels). These data also show that swelling-induced increases in [Ca2+](i) help modulate net ion efflux during regulation.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume268
Issue number3 37-3
StatePublished - 1995
Externally publishedYes

Fingerprint

Swelling
Egtazic Acid
epithelial cells
Epithelial Cells
Ions
calcium
Gramicidin
Quinine
Water
Tetradecanoylphorbol Acetate
Chelating Agents
ions
Recovery
Cell Size
Ether
cells
Depolarization
Epithelium
gramicidin
Esters

Keywords

  • aqueous humor formation
  • ciliary epithelium
  • membrane transport
  • volume regulation
  • volume-induced ion channel activation

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Agricultural and Biological Sciences(all)

Cite this

Mechanisms of regulatory volume decrease in nonpigmented human ciliary epithelial cells. / Adorante, J. S.; Cala, Peter M.

In: American Journal of Physiology - Cell Physiology, Vol. 268, No. 3 37-3, 1995.

Research output: Contribution to journalArticle

@article{df4bdada719a4146b7ef432614e7a46d,
title = "Mechanisms of regulatory volume decrease in nonpigmented human ciliary epithelial cells",
abstract = "To study the net solute and water efflux pathways of the ciliary epithelium we employed a cultured human NPE cell line. Because of the possible relationship between transepithelial ion and water flux and cell volume regulation, the ion efflux pathways mediating regulatory volume decrease (RVD) were investigated. Osmotic swelling of NPE cells was followed by a volume recovery. Volume recovery was K+ dependent and inhibited by K+ channel blockers such as quinine (1 mM). After osmotic swelling, a Cl-- dependent membrane depolarization occurred that was inhibited by Cl- channel blockers such as 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 μM) or Ca2+ chelators such as ethylene glycolbis(β-aminoethyl ether)-N,N,N',N'- tetraacetic acid (EGTA, 2.0 mM). Cell swelling was also accompanied by an increase in intracellular Ca2+ concentration ([Ca2+](i)) of ~200 nM. The swelling-induced rise in [Ca2+](i) and RVD were diminished in the presence of 10 μM La3+, 50 nM 12-O-tetradecanoylphorbol 13-acetate, and nominally Ca2+-free medium. Near total blockage of RVD occurred after pretreatment of NPE cells with Ca2+-free EGTA-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA) acetoxymethyl ester-containing solutions. The inhibition of RVD by EGTA-BAPTA treatment was overcome by increasing K+ conductance with gramicidin. The above findings indicate that RVD in NPE cells is mediated by separate K+ and Cl- conductances (channels). These data also show that swelling-induced increases in [Ca2+](i) help modulate net ion efflux during regulation.",
keywords = "aqueous humor formation, ciliary epithelium, membrane transport, volume regulation, volume-induced ion channel activation",
author = "Adorante, {J. S.} and Cala, {Peter M}",
year = "1995",
language = "English (US)",
volume = "268",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "3 37-3",

}

TY - JOUR

T1 - Mechanisms of regulatory volume decrease in nonpigmented human ciliary epithelial cells

AU - Adorante, J. S.

AU - Cala, Peter M

PY - 1995

Y1 - 1995

N2 - To study the net solute and water efflux pathways of the ciliary epithelium we employed a cultured human NPE cell line. Because of the possible relationship between transepithelial ion and water flux and cell volume regulation, the ion efflux pathways mediating regulatory volume decrease (RVD) were investigated. Osmotic swelling of NPE cells was followed by a volume recovery. Volume recovery was K+ dependent and inhibited by K+ channel blockers such as quinine (1 mM). After osmotic swelling, a Cl-- dependent membrane depolarization occurred that was inhibited by Cl- channel blockers such as 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 μM) or Ca2+ chelators such as ethylene glycolbis(β-aminoethyl ether)-N,N,N',N'- tetraacetic acid (EGTA, 2.0 mM). Cell swelling was also accompanied by an increase in intracellular Ca2+ concentration ([Ca2+](i)) of ~200 nM. The swelling-induced rise in [Ca2+](i) and RVD were diminished in the presence of 10 μM La3+, 50 nM 12-O-tetradecanoylphorbol 13-acetate, and nominally Ca2+-free medium. Near total blockage of RVD occurred after pretreatment of NPE cells with Ca2+-free EGTA-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA) acetoxymethyl ester-containing solutions. The inhibition of RVD by EGTA-BAPTA treatment was overcome by increasing K+ conductance with gramicidin. The above findings indicate that RVD in NPE cells is mediated by separate K+ and Cl- conductances (channels). These data also show that swelling-induced increases in [Ca2+](i) help modulate net ion efflux during regulation.

AB - To study the net solute and water efflux pathways of the ciliary epithelium we employed a cultured human NPE cell line. Because of the possible relationship between transepithelial ion and water flux and cell volume regulation, the ion efflux pathways mediating regulatory volume decrease (RVD) were investigated. Osmotic swelling of NPE cells was followed by a volume recovery. Volume recovery was K+ dependent and inhibited by K+ channel blockers such as quinine (1 mM). After osmotic swelling, a Cl-- dependent membrane depolarization occurred that was inhibited by Cl- channel blockers such as 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 μM) or Ca2+ chelators such as ethylene glycolbis(β-aminoethyl ether)-N,N,N',N'- tetraacetic acid (EGTA, 2.0 mM). Cell swelling was also accompanied by an increase in intracellular Ca2+ concentration ([Ca2+](i)) of ~200 nM. The swelling-induced rise in [Ca2+](i) and RVD were diminished in the presence of 10 μM La3+, 50 nM 12-O-tetradecanoylphorbol 13-acetate, and nominally Ca2+-free medium. Near total blockage of RVD occurred after pretreatment of NPE cells with Ca2+-free EGTA-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA) acetoxymethyl ester-containing solutions. The inhibition of RVD by EGTA-BAPTA treatment was overcome by increasing K+ conductance with gramicidin. The above findings indicate that RVD in NPE cells is mediated by separate K+ and Cl- conductances (channels). These data also show that swelling-induced increases in [Ca2+](i) help modulate net ion efflux during regulation.

KW - aqueous humor formation

KW - ciliary epithelium

KW - membrane transport

KW - volume regulation

KW - volume-induced ion channel activation

UR - http://www.scopus.com/inward/record.url?scp=0029105463&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029105463&partnerID=8YFLogxK

M3 - Article

C2 - 7534986

AN - SCOPUS:0029105463

VL - 268

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

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

SN - 1931-857X

IS - 3 37-3

ER -