Regulatory Volume Decrease by SV40-transformed Rabbit Corneal Epithelial Cells Requires Ryanodine-sensitive Ca2+-induced Ca2+ Release

Regulatory Volume Decrease by SV40-transformed Rabbit Corneal Epithelial Cells Requires... The relationship between relative cell volume and time-dependent changes in intracellular Ca2+ concentration ([Ca2+] i ) during exposure to hypotonicity was characterized in SV-40 transformed rabbit corneal epithelial cells (tRCE) (i). Light scattering measurements revealed rapid initial swelling with subsequent 97% recovery of relative cell volume (characteristic time (τ vr ) was 5.9 min); (ii). Fura2-fluorescence single-cell imaging showed that [Ca2+] i initially rose by 216% in 30 sec with subsequent return to near baseline level after another 100 sec. Both relative cell volume recovery and [Ca2+] i transients were inhibited by either: (a) Ca2+-free medium; (b) 5 mm Ni2+ (inhibitor of plasmalemma Ca2+ influx); (c) 10 μm cyclopiazonic acid, CPA (which causes depletion of intracellular Ca2+ content); or (d) 100 μm ryanodine (inhibitor of Ca2+ release from intracellular stores). To determine the temporal relationship between an increased plasmalemma Ca2+ influx and the emptying of intracellular Ca2+ stores during the [Ca2+] i transients, Mn2+ quenching of fura2-fluorescence was quantified. In the presence of CPA, hypotonic challenge increased plasmalemma Mn2+ permeability 6-fold. However, Mn2+ permeability remained unchanged during exposure to either: 1.100 μm ryanodine; 2.10 μm CPA and 100 μm ryanodine. This report for the first time documents the time dependence of the components of the [Ca2+] i transient required for a regulatory volume decrease (RVD). The results show that ryanodine sensitive Ca2+ release from an intracellular store leads to a subsequent increase in plasmalemma Ca2+ influx, and that both are required for cells to undergo RVD. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Regulatory Volume Decrease by SV40-transformed Rabbit Corneal Epithelial Cells Requires Ryanodine-sensitive Ca2+-induced Ca2+ Release

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 1997 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002329900250
Publisher site
See Article on Publisher Site

Abstract

The relationship between relative cell volume and time-dependent changes in intracellular Ca2+ concentration ([Ca2+] i ) during exposure to hypotonicity was characterized in SV-40 transformed rabbit corneal epithelial cells (tRCE) (i). Light scattering measurements revealed rapid initial swelling with subsequent 97% recovery of relative cell volume (characteristic time (τ vr ) was 5.9 min); (ii). Fura2-fluorescence single-cell imaging showed that [Ca2+] i initially rose by 216% in 30 sec with subsequent return to near baseline level after another 100 sec. Both relative cell volume recovery and [Ca2+] i transients were inhibited by either: (a) Ca2+-free medium; (b) 5 mm Ni2+ (inhibitor of plasmalemma Ca2+ influx); (c) 10 μm cyclopiazonic acid, CPA (which causes depletion of intracellular Ca2+ content); or (d) 100 μm ryanodine (inhibitor of Ca2+ release from intracellular stores). To determine the temporal relationship between an increased plasmalemma Ca2+ influx and the emptying of intracellular Ca2+ stores during the [Ca2+] i transients, Mn2+ quenching of fura2-fluorescence was quantified. In the presence of CPA, hypotonic challenge increased plasmalemma Mn2+ permeability 6-fold. However, Mn2+ permeability remained unchanged during exposure to either: 1.100 μm ryanodine; 2.10 μm CPA and 100 μm ryanodine. This report for the first time documents the time dependence of the components of the [Ca2+] i transient required for a regulatory volume decrease (RVD). The results show that ryanodine sensitive Ca2+ release from an intracellular store leads to a subsequent increase in plasmalemma Ca2+ influx, and that both are required for cells to undergo RVD.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 15, 1997

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