ALPHA(1B)-ADRENOCEPTOR-MEDIATED CALCIUM OSCILLATION IS SPECIFIC FOR THE S-PHASE IN CELL-CYCLE AND DEPENDENT ON THE EXTRACELLULAR CALCIUM

Using Chinese hamster ovary cells stably expressing alpha(1b)-adrenoce ptor (alpha(1b)AR) as a model, we examined the effect of the cell cycl e on the agonist-promoted intracellular [Ca2+](i) oscillation. In cell s synchronized into either the G(1) state or the M phase, no oscillato ry behavior was observed under any extracellular Ca2+ concentrations ( [Ca2+](o) less than or equal to 3 mM), whereas in cells synchronized i nto the S phase, norepinephrine caused [Ca2+](i) oscillation in a [Ca2 +](o)-dependent manner, indicating that alpha(1)AR-mediated [Ca2+](i) oscillation is specific for the S phase in cell cycle and dependent on [Ca2+](o). The S phase-specific occurrence of alpha(1)AR-mediated [Ca 2+](i) oscillation is not associated with changes in alpha(1)AR densit y. As the cells consistently developed [Ca2+](i) oscillation in the S phase, the cells would provide a valuable system to study further the biochemical mechanism for agonist-induced [Ca2+](i) oscillation phenom enon. (C) 1996 Academic Press, Inc.