STABLE EXPRESSION OF THE HUMAN LARGE-CONDUCTANCE CA2-ACTIVATED K+ CHANNEL ALPHA-SUBUNITS AND BETA-SUBUNITS IN HEK293 CELLS()

We have generated HEK293 cell lines stably expressing high levels of e ither the human BK channel alpha-subunit alone or the BK channel alpha -subunit and beta-subunit together. For co-expression a plasmid with t hree expression cassettes was constructed. Patch-clamp recordings on i nside-out patches from the transfected cells resulted in macroscopic c urrents reflecting the expression of 200-800 BK channels per patch, No decrease in channel expression could be detected in cells grown for m ore than 50 passages, The alpha-subunit when expressed alone conducted currents which were sensitive to intracellular Ca2+ in the physiologi cal range. In the presence of the beta-subunit the steady-state activa tion curves were shifted by -20 to -30 mV and channel deactivation kin etics were slowed, The BK channel opener NS1608 (10 mu M) shifted the steady-state activation curves for the alpha-subunit as well as for th e alpha beta-subunits by -40 to -50 mV. (C) 1997 Federation of Europea n Biochemical Societies.