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Osmotic and phorbol ester-induced activation of Na+/H+ exchange: possible role of protein phosphorylation in lymphocyte volume regulation.
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| Zeitschriftentitel: | The Journal of cell biology |
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| Personen und Körperschaften: | , , , |
| In: | The Journal of cell biology, 101, 1985, 1, S. 269-276 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
Rockefeller University Press
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| Schlagwörter: |
| Zusammenfassung: | <jats:p>The Na+/H+ antiport is stimulated by 12-O-tetradecanoylphorbol-13, acetate (TPA) and other phorbol esters in rat thymic lymphocytes. Mediation by protein kinase C is suggested by three findings: (a) 1-oleoyl-2-acetylglycerol also activated the antiport; (b) trifluoperazine, an inhibitor of protein kinase C, blocked the stimulation of Na+/H+ exchange; and (c) activation of countertransport was accompanied by increased phosphorylation of specific membrane proteins. The Na+/H+ antiport is also activated by osmotic cell shrinking. The time course, extent, and reversibility of the osmotically induced and phorbol ester-induced responses are similar. Moreover, the responses are not additive and they are equally susceptible to inhibition by trifluoperazine, N-ethylmaleimide, and ATP depletion. The extensive analogies between the TPA and osmotically induced effects suggested a common underlying mechanism, possibly activation of a protein kinase. It is conceivable that osmotic shrinkage initiates the following sequence of events: stimulation of protein kinase(s) followed by activation of the Na+/H+ antiport, resulting in cytoplasmic alkalinization. The Na+ taken up through the antiport, together with the HCO3- and Cl- accumulated in the cells as a result of the cytoplasmic alkalinization, would be followed by osmotically obliged water. This series of events could underlie the phenomenon of regulatory volume increase.</jats:p> |
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| Umfang: | 269-276 |
| ISSN: |
0021-9525
1540-8140 |
| DOI: | 10.1083/jcb.101.1.269 |