Calcium-Activated Potassium Channels in Human Platelets (42963)

Burton P. Fine, Kathleen A. Hansen, Jose R. Salcedo, Abraham Aviv

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10 Scopus citations


The cationic fluorescent probe, DiSC3(5) was used to measure the membrane potential in human platelets. Hyperpolarization was induced by the addition of Ca2+ to the medium and also by the addition of the Ca2+ ionophore, A23187. In the absence of extracellular Ca2+ ([Ca2+]o) there was no response to A23187. The threshold concentration for [Ca2+]o was 20 μM and for A23187 was 12 nM. The increase polarity induced by [Ca2+]o was not affected by various K+ channel blockers. However, the effect of A23187 was inhibited by quinine and charybdotoxin, while apamin, tetraethylammonium, and the calmodulin inhibitors trifluoperazine and compound R24571 were ineffective. The resting membrane potential was −66 ± 0.9 mV and was decreased by quinine. There are three conclusions from this study: (i) Ca2+-activated K+ channels exist in human platelets; (ii) they are the type that are apamin insensitive, charybdotoxin sensitive; and (iii) they may contribute to the resting membrane potential.

Original languageEnglish (US)
Pages (from-to)109-113
Number of pages5
JournalProceedings of the Society for Experimental Biology and Medicine
Issue number2
StatePublished - Nov 1989

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)


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