Distinct Ca2+-permeable Cation Currents Are Activated by Internal Ca2+-Store Depletion in RBL-2H3 Cells and Human Salivary Gland Cells, HSG and HSY

Distinct Ca2+-permeable Cation Currents Are Activated by Internal Ca2+-Store Depletion in RBL-2H3... Store-operated Ca2+ influx, suggested to be mediated via store-operated cation channel (SOC), is present in all cells. The molecular basis of SOC, and possible heterogeneity of these channels, are still a matter of controversy. Here we have compared the properties of SOC currents (I SOC) in human submandibular glands cells (HSG) and human parotid gland cells (HSY) with I CRAC (Ca2+ release-activated Ca2+ current) in RBL cells. Internal Ca2+ store-depletion with IP3 or thapsigargin activated cation channels in all three cell types. 1 μM Gd3+ blocked channel activity in all cells. Washout of Gd3+ induced partial recovery in HSY and HSG but not RBL cells. 2-APB reversibly inhibited the channels in all cells. I CRAC in RBL cells displayed strong inward rectification with E rev(Ca) = >+90 mV and E rev (Na) = +60 mV. I SOC in HSG cells showed weaker rectification with E rev(Ca) = +25 mV and E rev(Na) = +10 mV. HSY cells displayed a linear current with E rev = +5 mV, which was similar in Ca2+- or Na+-containing medium. pCa/pNa was >500, 40, and 4.6 while pCs /pNa was 0.1,1, and 1.3, for RBL, HSG, and HSY cells, respectively. Evidence for anomalous mole fraction behavior of Ca2+/Na+ permeation was obtained with RBL and HSG cells but not HSY cells. Additionally, channel inactivation with Ca2+ + Na+ or Na+ in the bath was different in the three cell types. In aggregate, these data demonstrate that distinct store-dependent cation currents are stimulated in RBL, HSG, and HSY cells. Importantly, these data suggest a molecular heterogeneity, and possibly cell-specific differences in the function, of these channels. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Distinct Ca2+-permeable Cation Currents Are Activated by Internal Ca2+-Store Depletion in RBL-2H3 Cells and Human Salivary Gland Cells, HSG and HSY

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Publisher
Springer-Verlag
Copyright
Copyright © 2004 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-004-0698-3
Publisher site
See Article on Publisher Site

Abstract

Store-operated Ca2+ influx, suggested to be mediated via store-operated cation channel (SOC), is present in all cells. The molecular basis of SOC, and possible heterogeneity of these channels, are still a matter of controversy. Here we have compared the properties of SOC currents (I SOC) in human submandibular glands cells (HSG) and human parotid gland cells (HSY) with I CRAC (Ca2+ release-activated Ca2+ current) in RBL cells. Internal Ca2+ store-depletion with IP3 or thapsigargin activated cation channels in all three cell types. 1 μM Gd3+ blocked channel activity in all cells. Washout of Gd3+ induced partial recovery in HSY and HSG but not RBL cells. 2-APB reversibly inhibited the channels in all cells. I CRAC in RBL cells displayed strong inward rectification with E rev(Ca) = >+90 mV and E rev (Na) = +60 mV. I SOC in HSG cells showed weaker rectification with E rev(Ca) = +25 mV and E rev(Na) = +10 mV. HSY cells displayed a linear current with E rev = +5 mV, which was similar in Ca2+- or Na+-containing medium. pCa/pNa was >500, 40, and 4.6 while pCs /pNa was 0.1,1, and 1.3, for RBL, HSG, and HSY cells, respectively. Evidence for anomalous mole fraction behavior of Ca2+/Na+ permeation was obtained with RBL and HSG cells but not HSY cells. Additionally, channel inactivation with Ca2+ + Na+ or Na+ in the bath was different in the three cell types. In aggregate, these data demonstrate that distinct store-dependent cation currents are stimulated in RBL, HSG, and HSY cells. Importantly, these data suggest a molecular heterogeneity, and possibly cell-specific differences in the function, of these channels.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2004

References

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