| Autor: |
G Theilmeier, S Kühnapfel, C Teupe, Martin Tepel, Walter Zidek, R Schlotmann |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Journal of Biological Chemistry. 269:26239-26242 |
| ISSN: |
0021-9258 |
| DOI: |
10.1016/s0021-9258(18)47185-2 |
| Popis: |
The relations between the filling state of intracellular calcium stores that are regulated by the endoplasmic Ca(2+)-ATPase and trans plasma membrane sodium and calcium influx were investigated. The effects of specific inhibition of endoplasmic Ca(2+)-ATPase by thapsigargin, cyclopiazonic acid, and 2,5-di-(tert-butyl)-1,4-benzohydroquinone (BHQ) on cytosolic free sodium concentration ([Na+]i) and cytosolic free calcium concentration ([Ca2+]i) were evaluated in lymphocytes from healthy subjects using the fluorescent dyes sodium-binding benzofuran isophthalate and fura2. The specific inhibition of endoplasmic Ca(2+)-ATPase by thapsigargin, cyclopiazonic acid, or BHQ increased lymphocytic [Na+]i and [Ca2+]i. The thapsigargin-induced [Na+]i increase was abolished in the absence of external sodium, indicating that thapsigargin induced a trans plasma membrane sodium influx. In the absence of external calcium the thapsigargin-induced [Ca2+]i increase was significantly reduced, whereas the thapsigargin-induced [Na+]i increase remained the same. This finding indicates that the filling state of intracellular calcium pools rather than the elevation of [Ca2+]i per se regulates the plasma membrane permeability for sodium in lymphocytes. The inhibition of the tyrosine kinase by genistein inhibited the thapsigargin-induced increases of both [Na+]i and [Ca2+]i in lymphocytes. The present study shows that the filling state of intracellular thapsigargin-sensitive calcium pools regulates trans plasma membrane sodium and calcium influx via a tyrosine kinase-dependent pathway. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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