Regulation of Ca~(2+) Influx in Proliferating and Differentiating Murine Myoblasts with Participation of L-type Ca~(2+) Channels

摘要

The basic mechanisms of regulation of Ca~(2+) influx have been studied in murine myoblasts prolif erating and differentiating in culture. The presence of Ltype Ca~(2+) channels in proliferating myoblasts is shown for the first time. It is also shown that the influx of Ca~(2+) through these channels is regulated by the adrenergic system. The influx of Ca~(2+) after activation of the adrenergic system by addition of adrenaline has been estimated in comparison with the contribution of reticular stocks exhausted by ATP in calciumfree medium. The Ca~(2+) influx in proliferating myoblasts is regulated by β2 adrenergic receptors whose action is mediated by adenylate cyclase through Ltype calcium channels. In differentiating myoblasts, the adrena lineinduced Ca~(2+) influx is substantially lower than in proliferating cells, and maximal influx of Ca~(2+) may be reached only upon exhaustion of reticular stocks.