Alpha 1b-adrenoceptor-mediated calcium oscillation is specific for the S phase in cell cycle and dependent on the...

Using Chinese hamster ovary cells stably expressing alpha 1b-adrenoceptor (alpha 1bAR) as a model, we examined the effect of the cell cycle on the agonist-promoted intracellular [Ca2+]i oscillation. In cells synchronized into either the G1 state or the M phase, no oscillatory behavior was observed under any extracellular Ca2+ concentrations ([Ca2+]o < or = 3 mM), whereas in cells synchronized into the S phase, norepinephrine caused [Ca2+]i oscillation in a [Ca2+]o-dependent manner, indicating that alpha 1AR-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 1AR-mediated [Ca2+]i oscillation is not associated with changes in alpha 1AR density. 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 phenomenon.