Calcium-activated sodium and chloride fluxes modulate platelet volume: role of Ca2+ stores.
Am J Physiol
; 267(5 Pt 1): C1435-41, 1994 Nov.
Article
em En
| MEDLINE
| ID: mdl-7977704
An increase in cytosolic ionized Ca2+ concentration ([Ca2+]i) initiates volume changes in various types of cells. In response to increases in [Ca2+]i most cell types contract by efflux of K+ and Cl-, whereas platelets expand in response to rises in [Ca2+]i. This study examined the importance of the source of Ca2+, the flux of ions responsible for the volume change, and the role of Ca(2+)-dependent protein kinases in regulating these ionic fluxes. The baseline platelet volume was independent of extracellular Ca2+ but when stimulated by the Ca2+ ionophore A-23187 (50 nM) the volume increased in both the presence and absence of extracellular Ca2+ (1.18 +/- 0.08 vs. 0.83 +/- 0.06 fl, respectively). The increased volume was caused by the gain of Na+ and Cl-. Na+ entered through both conductive and nonconductive (Na+/H+ exchange) pathways, whereas the influx of Cl- was conductive and inhibited by the Cl- channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. The Ca(2+)-induced volume change was blocked by both calmodulin and protein kinase inhibitors. Thus the activation of Ca(2+)-dependent protein kinases promotes platelet swelling by stimulating Na+ and Cl- influx.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Plaquetas
/
Cloretos
/
Cálcio
Limite:
Humans
Idioma:
En
Ano de publicação:
1994
Tipo de documento:
Article