The influence of sodium-calcium exchange inhibitors on rabbit lens ion balance and transparency

Shigeo Tamiya, Nicholas A Delamere

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Calcium regulation is essential to the maintenance of lens transparency. To maintain cytoplasmic calcium concentration at the required low level the lens must export calcium continuously. Here, studies were conducted to test whether sodium-calcium exchanger (NCX) inhibitors disturb calcium balance in the rabbit lens. Intact lenses were incubated up to 48 h in the presence or absence of the NCX inhibitor bepridil. Lens sodium, potassium and calcium content were determined by atomic absorption spectrophotometry. Fluo-4 was used to measure epithelial cell cytoplasmic calcium concentration in an intact lens preparation. NCX1 protein expression in lens epithelium was examined by western blot. NCX1 band density was similar in central and equatorial epithelium samples. Lenses exposed to bepridil (30 μM) lost transparency at the anterior and exhibited significant changes in electrolyte and water content. After 48 h, lens calcium content more than doubled, sodium increased four fold and potassium was significantly reduced. In contrast, lenses exposed to inhibitors of reverse mode calcium transport by NCX (KBR7943 or SN-6) remained transparent and the electrolyte and water content of the lens remained unchanged. The ability of bepridil to cause significant changes in lens transparency and electrolyte content points to an important role for NCX-meditated calcium export in the lens.

Original languageEnglish (US)
Pages (from-to)1089-1095
Number of pages7
JournalExperimental Eye Research
Volume83
Issue number5
DOIs
StatePublished - Nov 2006
Externally publishedYes

Fingerprint

Lenses
Sodium
Ions
Rabbits
Calcium
Bepridil
Electrolytes
Potassium
Epithelium
Sodium-Calcium Exchanger
Atomic Spectrophotometry
Water
Western Blotting
Epithelial Cells
Maintenance

Keywords

  • calcium
  • hydration
  • lens
  • Na-Ca exchange
  • sodium
  • transparency

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Cite this

The influence of sodium-calcium exchange inhibitors on rabbit lens ion balance and transparency. / Tamiya, Shigeo; Delamere, Nicholas A.

In: Experimental Eye Research, Vol. 83, No. 5, 11.2006, p. 1089-1095.

Research output: Contribution to journalArticle

@article{e2ce8e5891bf46498e5b1fa017bdd842,
title = "The influence of sodium-calcium exchange inhibitors on rabbit lens ion balance and transparency",
abstract = "Calcium regulation is essential to the maintenance of lens transparency. To maintain cytoplasmic calcium concentration at the required low level the lens must export calcium continuously. Here, studies were conducted to test whether sodium-calcium exchanger (NCX) inhibitors disturb calcium balance in the rabbit lens. Intact lenses were incubated up to 48 h in the presence or absence of the NCX inhibitor bepridil. Lens sodium, potassium and calcium content were determined by atomic absorption spectrophotometry. Fluo-4 was used to measure epithelial cell cytoplasmic calcium concentration in an intact lens preparation. NCX1 protein expression in lens epithelium was examined by western blot. NCX1 band density was similar in central and equatorial epithelium samples. Lenses exposed to bepridil (30 μM) lost transparency at the anterior and exhibited significant changes in electrolyte and water content. After 48 h, lens calcium content more than doubled, sodium increased four fold and potassium was significantly reduced. In contrast, lenses exposed to inhibitors of reverse mode calcium transport by NCX (KBR7943 or SN-6) remained transparent and the electrolyte and water content of the lens remained unchanged. The ability of bepridil to cause significant changes in lens transparency and electrolyte content points to an important role for NCX-meditated calcium export in the lens.",
keywords = "calcium, hydration, lens, Na-Ca exchange, sodium, transparency",
author = "Shigeo Tamiya and Delamere, {Nicholas A}",
year = "2006",
month = "11",
doi = "10.1016/j.exer.2006.05.014",
language = "English (US)",
volume = "83",
pages = "1089--1095",
journal = "Experimental Eye Research",
issn = "0014-4835",
publisher = "Academic Press Inc.",
number = "5",

}

TY - JOUR

T1 - The influence of sodium-calcium exchange inhibitors on rabbit lens ion balance and transparency

AU - Tamiya, Shigeo

AU - Delamere, Nicholas A

PY - 2006/11

Y1 - 2006/11

N2 - Calcium regulation is essential to the maintenance of lens transparency. To maintain cytoplasmic calcium concentration at the required low level the lens must export calcium continuously. Here, studies were conducted to test whether sodium-calcium exchanger (NCX) inhibitors disturb calcium balance in the rabbit lens. Intact lenses were incubated up to 48 h in the presence or absence of the NCX inhibitor bepridil. Lens sodium, potassium and calcium content were determined by atomic absorption spectrophotometry. Fluo-4 was used to measure epithelial cell cytoplasmic calcium concentration in an intact lens preparation. NCX1 protein expression in lens epithelium was examined by western blot. NCX1 band density was similar in central and equatorial epithelium samples. Lenses exposed to bepridil (30 μM) lost transparency at the anterior and exhibited significant changes in electrolyte and water content. After 48 h, lens calcium content more than doubled, sodium increased four fold and potassium was significantly reduced. In contrast, lenses exposed to inhibitors of reverse mode calcium transport by NCX (KBR7943 or SN-6) remained transparent and the electrolyte and water content of the lens remained unchanged. The ability of bepridil to cause significant changes in lens transparency and electrolyte content points to an important role for NCX-meditated calcium export in the lens.

AB - Calcium regulation is essential to the maintenance of lens transparency. To maintain cytoplasmic calcium concentration at the required low level the lens must export calcium continuously. Here, studies were conducted to test whether sodium-calcium exchanger (NCX) inhibitors disturb calcium balance in the rabbit lens. Intact lenses were incubated up to 48 h in the presence or absence of the NCX inhibitor bepridil. Lens sodium, potassium and calcium content were determined by atomic absorption spectrophotometry. Fluo-4 was used to measure epithelial cell cytoplasmic calcium concentration in an intact lens preparation. NCX1 protein expression in lens epithelium was examined by western blot. NCX1 band density was similar in central and equatorial epithelium samples. Lenses exposed to bepridil (30 μM) lost transparency at the anterior and exhibited significant changes in electrolyte and water content. After 48 h, lens calcium content more than doubled, sodium increased four fold and potassium was significantly reduced. In contrast, lenses exposed to inhibitors of reverse mode calcium transport by NCX (KBR7943 or SN-6) remained transparent and the electrolyte and water content of the lens remained unchanged. The ability of bepridil to cause significant changes in lens transparency and electrolyte content points to an important role for NCX-meditated calcium export in the lens.

KW - calcium

KW - hydration

KW - lens

KW - Na-Ca exchange

KW - sodium

KW - transparency

UR - http://www.scopus.com/inward/record.url?scp=33748682313&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33748682313&partnerID=8YFLogxK

U2 - 10.1016/j.exer.2006.05.014

DO - 10.1016/j.exer.2006.05.014

M3 - Article

VL - 83

SP - 1089

EP - 1095

JO - Experimental Eye Research

JF - Experimental Eye Research

SN - 0014-4835

IS - 5

ER -