Hazelton B J, Tupper J T
J Cell Biol. 1979 Jun;81(3):538-42. doi: 10.1083/jcb.81.3.538.
The kinetics of Ca++ uptake have been evaluated in 3T3 and SV40-3T3 mouse cells. The data reveal at least two exchangeable cellular compartments in the 3T3 and SV40-3T3 cell over a 50-min exposure to 45Ca++. A rapidly exchanging compartment may represent surface-membrane-localized Ca++ whereas a more slowly exchanging compartment is presumably intracellular. The transition of the 3T3 cell from exponential growth (at 3 day's incubation) to quiescence (at 7 days) is characterized by a 7.5-fold increase in the size of the fast component. Quiescence of the 3T3 cell is also characterized by a 3.2-fold increase in the unidirectional Ca++ influx into the slowly exchanging compartment and a 3.6-fold increase in its size. The increase in size of the slow compartment at quiescence may result from a redistribution of intracellular Ca++ to a more readily exchangeable compartment, possibly reflecting a release of previously bound Ca++. In contrast, no significant change in any of these parameters is observed in the proliferatively active SV40-3T3 cells after corresponding period of incubation, even though these cells attained higher growth densities and underwent postconfluence.
已在3T3和SV40 - 3T3小鼠细胞中评估了Ca++摄取的动力学。数据显示，在暴露于45Ca++ 50分钟的过程中，3T3和SV40 - 3T3细胞中至少存在两个可交换的细胞区室。一个快速交换的区室可能代表位于表面膜的Ca++，而一个交换较慢的区室可能位于细胞内。3T3细胞从指数生长（培养3天）转变为静止状态（培养7天）的特征是快速成分的大小增加了7.5倍。3T3细胞静止状态的另一个特征是进入缓慢交换区室的单向Ca++流入增加了3.2倍，其大小增加了3.6倍。静止时缓慢区室大小的增加可能是由于细胞内Ca++重新分布到一个更易于交换的区室，这可能反映了先前结合的Ca++的释放。相比之下，在相应的培养期后，即使增殖活跃的SV40 - 3T3细胞达到了更高的生长密度并经历了汇合后阶段，这些参数中也没有观察到任何显著变化。
