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| Item Type: | Article |
|---|---|
| Title: | Sodium block and depolarization diminish P2Z-dependent Ca2+ entry in human B lymphocytes |
| Creators Name: | Loehn, M., Klapperstueck, M., Riemann, D. and Markwardt, F. |
| Abstract: | Despite a high Ca2+-permeability of the P2Z receptor in human B lymphocytes, extracellular ATP4- has only a minor effect on global [Ca2+]i. The aim of this study was to reveal the mechanisms responsible for this discrepancy. We investigated the relationship between ATP4-application, Cai 2+-response, membrane current and membrane potential in two human B cell lines and in human tonsillar B cells. This was achieved by a combination of FACS- and voltage clamp measurements and the usage of appropriate voltage- and Ca2+-sensitive fluorescent dyes. ATP4-induced changes in whole-cell current and [Ca2+]i were blocked by extracellular as well as intracellular Na+. Under current clamp conditions, ATP4--induced Na+-entry diminished the Ca2+ entry via reduction of the driving force. A substantial increase in [Ca2+-]i induced by ATP4- was only observed in Na+-free solutions. The pathway of signal transduction activated by ATP4- via P2Z receptor of human B lymphocytes under physiological conditions seems not to operate by an increase in the global intracellular Ca2+-concentration, but rather by the depolarization of the cell membrane as a result of the Na+-influx. |
| Keywords: | Adenosine Triphosphate, B-Lymphocytes, Calcium, Cell Membrane, Cultured Cells, Extracellular Space, Flow Cytometry, Membrane Potentials, Purinergic P2 Receptors, Signal Transduction, Sodium, Tonsil |
| Source: | Cell Calcium |
| ISSN: | 0143-4160 |
| Publisher: | Elsevier |
| Volume: | 29 |
| Number: | 6 |
| Page Range: | 395-408 |
| Date: | 1 January 2001 |
| PubMed: | View item in PubMed |
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