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Activation of sodium‐proton exchange is not a prerequisite for Ca 2+ mobilization and aggregation in human platelets
Author(s) -
Hunyady László,
Sarkadi Balázs,
Cragoe Edward J.,
Spät András,
Gárdos George
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81133-x
Subject(s) - chemistry , biophysics , sodium , platelet , amiloride , platelet activation , sodium–hydrogen antiporter , ion exchange , medicine , ion , biology , organic chemistry
Recently it has been suggested [(1987) Nature 325, 456–458; (1987) FEBS Lett. 212, 123–126] that the activation of Na + /H + exchange is a prerequisite for platelet aggregation and the development of the Ca 2+ signal. As direct evidence for the role of the Na + /H + ‐exchange pathway the inhibition of the Ca 2+ signal by EIPA, a specific inhibitor of Na + /H + exchange, was offered. Here we demonstrate that low concentrations of EIPA (below 1 μM) completely block Na + /H + exchange while EIPA inhibits aggregation or Ca 2+ mobilization only in concentrations 100‐times greater than 1 μM. Moreover, another amiloride analogue, CBDMB, developed to act predominantly on Na + /Ca 2+ exchange, does not affect Na + /H + exchange in platelets but blocks aggregation and Ca 2+ mobilization. We conclude that while Na + /H + exchange has a fundamental role in platelet functions it is not prerequisite for the development of Ca 2+ signal and aggregation.