The pharmacology of hSK1 Ca2+-activated K+ channels expressed in mammalian cell lines.
The pharmacology of hSK1, a small conductance calcium-activated potassium channel, was studied in mammalian cell lines (HEK293 and COS-7). In these cell types, hSK1 forms an apamin-sensitive channel with an IC(50) for apamin of 8 nM in HEK293 cells and 12 nM in COS-7 cells. The currents in HEK293 cells were also sensitive to tubocurarine (IC(50)=23 microM), dequalinium (IC(50)=0.4 microM), and the novel dequalinium analogue, UCL1848 (IC(50)=1 nM). These results are very different from the pharmacology of hSK1 channels expressed in Xenopus oocytes and suggest the properties of the channel may depend on the expression system. Our findings also raise questions about the role of SK1 channels in generating the apamin-insensitive slow afterhyperpolarization observed in central neurones.
Shah
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Department of Pharmacology, University College London, Gower Street, London, WC1E 6BT.
Haylett
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D000818:Animals; D001030:Apamin / Q000494:pharmacology; D019556:COS Cells; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D003868:Dequalinium / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000166:cytology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated; D051381:Rats; D051640:Small-Conductance Calcium-Activated Potassium Channels; D014162:Transfection; D014403:Tubocurarine / Q000494:pharmacology; D014981:Xenopus
C496894:KCNN1 protein, human; C496896:Kcnn1 protein, rat; D018733:Nicotinic Antagonists; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin; D003868:Dequalinium; D002118:Calcium; D014403:Tubocurarine