GENERATION OF CELL TRANSFECTANTS EXPRESSING CARDIAC CALCIUM-ION CHANNEL AND CALCIUM INDICATOR PROTEIN AEQUORIN

Chinese hamster ovary (CHO) cells stably coexpressing cardiac calcium ion channel [L-type calcium channel or ryanodine receptor (RyR)] and t he calcium-sensitive bioluminescent protein aequorin were generated by transfecting aequorin cDNA. In a selected clone, C1-17, carrying the L-type calcium channel, depolarization induced by high concentration o f Ki produces aequorin luminescence, In another clone, R3-7, carrying RyR, caffeine produces aequorin luminescence. In the presence of selec tive calcium ion channel blockers, the aequorin luminescence was inhib ited in a dose-dependent manner, These results indicate that functiona lly expressed calcium ion channels in these transformants can be monit ored through the activation of endogenous aequorin luminescence follow ing a physiological signal similar to that of native calcium channel. Moreover, the aequorin system compared very well with Fura-8 measureme nts, Thus, the recombinant cell models, which expressed cloned calcium channel and aequorin, will contribute to the elucidation of Ca2+ move ment through the cell surface and intracellular calcium ion channels. (C) 1996 Academic Press, Inc.