The block of the expressed L-type calcium channel is modulated by the beta 3 subunit

The alpha 1C subunit of the L-type calcium channel was stable, expressed alone or in combination with the beta 3 subunit in Chinese hamster ovary cells. The beta 3 subunit enhanced significantly the inactivation of barium currents indicating that both subunits interacted with each other. The beta 3 subunit decreased significantly the half-maximal inhibitory concentration of the calcium channel blockers (-)-gallopamil and verapamil, but did not affect significantly the block caused by isradipine and mibefradil at the holding potentials of -80 mV and -40 mV. These results suggest that the beta 3 subunit affects distinctly the interaction of the expressed alpha 1C subunit with different classes of organic calcium channel blockers.