Molecular characterization of volume-sensitive SK(Ca) channels in human liver cell lines.

In human liver, Ca(2+)-dependent changes in membrane K(+) permeability play a central role in coordinating functional interactions between membrane transport, metabolism, and cell volume. On the basis of the observation that K(+) conductance is partially sensitive to the bee venom toxin apamin, we aimed to assess whether small-conductance Ca(2+)-sensitive K(+) (SK(Ca)) channels are expressed endogenously and contribute to volume-sensitive K(+) efflux and cell volume regulation. We isolated a full-length 2,140-bp cDNA (hSK2) highly homologous to rat brain rSK2 cDNA, including the putative apamin-sensitive pore domain, from a human liver cDNA library.