Zetterberg A, Engström W
Proc Natl Acad Sci U S A. 1981 Jul;78(7):4334-8. doi: 10.1073/pnas.78.7.4334.
The effect of environmental pH on the proliferative activity of sparse 3T3 cell cultures was investigated. When quiescent (serum-starved) cells were transferred to a serum-depleted medium in which pH had been elevated, cell proliferation was stimulated during the first 24 hr after the medium change, as reflected by an increase in cell number and in the proportion of cells synthesizing DNA (measured by autoradiography and flow cytophotometry). The growth-stimulatory effect was greater with increasing pH. At pH 8.2 the effect was approximately 50% of that seen in serum-stimulated cells (i.e., upon the addition of 10% serum). Above pH 8.2 toxic effects and cell death were observed. However, the stimulatory effect could be performed without interference of toxic effects by exposing the cells to the high alkaline environment for a short period. A maximum stimulatory effect on the quiescent cells--without any observed toxic effects--was seen after exposure to an alkaline pulse with a duration of 2-10 min at a pH between 8.5 and 10. More than 80% of the cells synthesized DNA during the first 24 hr after the alkaline-pulse stimulation, which is an almost similar response to that seen after stimulation with serum. The growth-stimulatory effect of the alkaline-pulse treatment could not be prevented by a subsequent treatment at acid pH. Kinetic analysis revealed that DNA synthesis was not initiated until 9-12 hr after the alkaline-pulse treatment. This lag period was of the same length as that seen after stimulation with serum. Alkaline-pulse treatment only resulted in stimulation of DNA synthesis and mitosis during one cell cycle. When the alkaline treatment was repeated, only a small proportion of cells could proceed through a second cell cycle.
研究了环境pH对稀疏3T3细胞培养物增殖活性的影响。当静止(血清饥饿)细胞转移到pH升高的无血清培养基中时,在更换培养基后的最初24小时内细胞增殖受到刺激,这可通过细胞数量增加以及合成DNA的细胞比例增加(通过放射自显影和流式细胞光度法测量)来反映。随着pH升高,生长刺激作用增强。在pH 8.2时,该作用约为血清刺激细胞(即添加10%血清时)的50%。在pH 8.2以上观察到毒性作用和细胞死亡。然而,通过使细胞短时间暴露于高碱性环境中,可在无毒性作用干扰的情况下发挥刺激作用。在pH 8.5至10之间进行持续2 - 10分钟的碱性脉冲处理后,对静止细胞观察到最大刺激作用且无任何毒性作用。在碱性脉冲刺激后的最初24小时内,超过80%的细胞合成了DNA,这与血清刺激后的反应几乎相似。碱性脉冲处理的生长刺激作用不能被随后的酸性pH处理所阻止。动力学分析表明,直到碱性脉冲处理后9 - 12小时才开始DNA合成。这个延迟期与血清刺激后的长度相同。碱性脉冲处理仅在一个细胞周期内刺激DNA合成和有丝分裂。当重复碱性处理时,只有一小部分细胞能够进入第二个细胞周期。