Thrombin-induced changes of intracellular [Ca2+] and pH in human platelets. Cytoplasmic alkalinization is not a prerequisite for calcium mobilization.
Biochim Biophys Acta
; 938(3): 497-500, 1988 Mar 03.
Article
em En
| MEDLINE
| ID: mdl-2831984
ABSTRACT
We have studied the effects of thrombin (0.1 U/ml) on intracellular Ca2+ ([Ca2+]i) and pH (pHi) in human platelets loaded with fluorescent indicators. Thrombin produced a transient decrease of pHi which reached its maximum within 15-25 seconds (s) and was followed by a sustained alkalinization which brought pHi above the resting value. [Ca2+]i increased transiently peaking at 5-10 s. The late alkalinization induced by thrombin was antagonized by ethylisopropylamiloride, an inhibitor of Na+-H+ exchange, and by sphingosine, an inhibitor of protein kinase C, with little effect on the [Ca2+]i transient. The early acidification was not inhibited by these treatments. We conclude tha the thrombin-induced changes of [Ca2+]i and pHi are mediated by different mechanisms. The late alkalinization is due to activation of Na+/H+ exchange mediated by protein kinase C and, contrarily to previous proposals (Siffert, W. and Akkerman, J.W.N. (1987) Nature 325, 456-458), it is not necessary for calcium mobilization from intracellular stores.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Plaquetas
/
Trombina
/
Cálcio
Limite:
Humans
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1988
Tipo de documento:
Article
País de afiliação:
Espanha