Abstract
The role of the Na+/Ca2+ exchanger in intracellular Ca2+ regulation was investigated in freshly dissociated catfish retinal horizontal cells (HC). Ca2+-permeable glutamate receptors and L-type Ca2+ channels as well as inositol 1,4,5-trisphosphate-sensitive and caffeine-sensitive intracellular Ca2+ stores regulate intracellular Ca2+ in these cells. We used the Ca2+-sensitive dye flue 3 to measure changes in intracellular Ca2+ concentration ([Ca2+]i) under conditions in which Na+/Ca2+ exchange was altered. In addition, the role of the Na+/Ca2+ exchanger in the refilling of the caffeine-sensitive Ca2+ store following caffeine- stimulated Ca2+ release was assessed. Brief applications of caffeine (1-10 s) produced rapid and transient changes in [Ca2+]i. Repeated applications of caffeine produced smaller Ca2+ transients until no further Ca2+ was released. Store refilling occurred within 1-2 min and required extracellular Ca2+. Ouabain-induced increases in intracellular Na+ concentration ([Na+](i)) increased both basal free [Ca2+](i) and caffeine-stimulated Ca2+ release. Reduction of external Na+ concentration ([Na+](o)) further and reversibly increased [Ca2+](i) in ouabain-treated HC. This effect was not abolished by the Ca2+ channel blocker nifedipine, suggesting that increases in [Na+](i) promote net extracellular Ca2+ influx through a Na+/Ca2+ exchanger. Moreover, when [Na+](o) was replaced by Li+, caffeine did not stimulate release of Ca2+ from the caffeine-sensitive store after Ca2+ depletion. The Na+/Ca2+ exchanger inhibitor 2',4'- dimethylbenzamil significantly reduced the caffeine-evoked Ca2+ response I and 2 min after store depletion.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 274 |
| Issue number | 6 43-6 |
| State | Published - Jun 1998 |
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Keywords
- Caffeine
- Fluo 3
- Retina
- Ryanodine receptor
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
- Physiology (medical)
Cite this
Na+/Ca2+ exchange in catfish retina horizontal cells : Regulation of intracellular Ca2+ store function. / Micci, Maria; Christensen, Burgess N.
In: American Journal of Physiology - Cell Physiology, Vol. 274, No. 6 43-6, 06.1998.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Na+/Ca2+ exchange in catfish retina horizontal cells
T2 - Regulation of intracellular Ca2+ store function
AU - Micci, Maria
AU - Christensen, Burgess N.
PY - 1998/6
Y1 - 1998/6
N2 - The role of the Na+/Ca2+ exchanger in intracellular Ca2+ regulation was investigated in freshly dissociated catfish retinal horizontal cells (HC). Ca2+-permeable glutamate receptors and L-type Ca2+ channels as well as inositol 1,4,5-trisphosphate-sensitive and caffeine-sensitive intracellular Ca2+ stores regulate intracellular Ca2+ in these cells. We used the Ca2+-sensitive dye flue 3 to measure changes in intracellular Ca2+ concentration ([Ca2+]i) under conditions in which Na+/Ca2+ exchange was altered. In addition, the role of the Na+/Ca2+ exchanger in the refilling of the caffeine-sensitive Ca2+ store following caffeine- stimulated Ca2+ release was assessed. Brief applications of caffeine (1-10 s) produced rapid and transient changes in [Ca2+]i. Repeated applications of caffeine produced smaller Ca2+ transients until no further Ca2+ was released. Store refilling occurred within 1-2 min and required extracellular Ca2+. Ouabain-induced increases in intracellular Na+ concentration ([Na+](i)) increased both basal free [Ca2+](i) and caffeine-stimulated Ca2+ release. Reduction of external Na+ concentration ([Na+](o)) further and reversibly increased [Ca2+](i) in ouabain-treated HC. This effect was not abolished by the Ca2+ channel blocker nifedipine, suggesting that increases in [Na+](i) promote net extracellular Ca2+ influx through a Na+/Ca2+ exchanger. Moreover, when [Na+](o) was replaced by Li+, caffeine did not stimulate release of Ca2+ from the caffeine-sensitive store after Ca2+ depletion. The Na+/Ca2+ exchanger inhibitor 2',4'- dimethylbenzamil significantly reduced the caffeine-evoked Ca2+ response I and 2 min after store depletion.
AB - The role of the Na+/Ca2+ exchanger in intracellular Ca2+ regulation was investigated in freshly dissociated catfish retinal horizontal cells (HC). Ca2+-permeable glutamate receptors and L-type Ca2+ channels as well as inositol 1,4,5-trisphosphate-sensitive and caffeine-sensitive intracellular Ca2+ stores regulate intracellular Ca2+ in these cells. We used the Ca2+-sensitive dye flue 3 to measure changes in intracellular Ca2+ concentration ([Ca2+]i) under conditions in which Na+/Ca2+ exchange was altered. In addition, the role of the Na+/Ca2+ exchanger in the refilling of the caffeine-sensitive Ca2+ store following caffeine- stimulated Ca2+ release was assessed. Brief applications of caffeine (1-10 s) produced rapid and transient changes in [Ca2+]i. Repeated applications of caffeine produced smaller Ca2+ transients until no further Ca2+ was released. Store refilling occurred within 1-2 min and required extracellular Ca2+. Ouabain-induced increases in intracellular Na+ concentration ([Na+](i)) increased both basal free [Ca2+](i) and caffeine-stimulated Ca2+ release. Reduction of external Na+ concentration ([Na+](o)) further and reversibly increased [Ca2+](i) in ouabain-treated HC. This effect was not abolished by the Ca2+ channel blocker nifedipine, suggesting that increases in [Na+](i) promote net extracellular Ca2+ influx through a Na+/Ca2+ exchanger. Moreover, when [Na+](o) was replaced by Li+, caffeine did not stimulate release of Ca2+ from the caffeine-sensitive store after Ca2+ depletion. The Na+/Ca2+ exchanger inhibitor 2',4'- dimethylbenzamil significantly reduced the caffeine-evoked Ca2+ response I and 2 min after store depletion.
KW - Caffeine
KW - Fluo 3
KW - Retina
KW - Ryanodine receptor
UR - http://www.scopus.com/inward/record.url?scp=0032088036&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032088036&partnerID=8YFLogxK
M3 - Article
VL - 274
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
SN - 0193-1849
IS - 6 43-6
ER -