Melvin M A, Keir H M
Biochem J. 1979 Feb 15;178(2):391-5. doi: 10.1042/bj1780391.
Cultures of BHK-21/C13 cells, whose growth was inhibited by deprivation of serum, were stimulated to grow by addition of serum to the culture medium. Addition of MgCl(2) to the medium, to increase the concentration of Mg(2+) ions by 15mm, 30min before addition of serum, had no effect on the stimulation of cell growth, but inhibited the accumulation of cellular spermidine, so that the spermidine/spermine molar ratio was lower in these cultures than in cultures that had received no additional cations. The increase in the activity of ornithine decarboxylase that occurs 4-5h after serum ;step-up' was substantially diminished by increasing the concentration of Mg(2+) ions, but not of Na(+) or K(+) ions, in the medium by 30mm, 30min before addition of serum, and this inhibition was maintained for at least 24h. Methylglyoxal bis(guanylhydrazone), added to serum-deprived cultures to a concentration of 20mum, 30min before addition of serum, severely inhibited the increase in cell growth. The inhibitory effects of the drug were prevented by simultaneous addition of spermidine to the medium (to 100mum), and were partly prevented by the simultaneous addition of Mg(2+) ions (to 30mm). Mg(2+) ions were particularly effective in overcoming the inhibitory effect of methylglyoxal bis(guanylhydrazone) on the synthesis of DNA. Thus although a certain lack of specificity for cations exists in BHK-21/C13 cells, in that Mg(2+) ions can be substituted for polyamines, particularly spermidine, to some extent, there are cellular processes for which the requirement for polyamines as cations is specific.
BHK - 21/C13细胞的培养物在血清剥夺下生长受到抑制，通过向培养基中添加血清来刺激其生长。在添加血清前30分钟向培养基中添加MgCl₂，使Mg²⁺离子浓度增加15mM，对细胞生长的刺激没有影响，但抑制了细胞内亚精胺的积累，因此这些培养物中的亚精胺/精胺摩尔比低于未添加额外阳离子的培养物。在血清“增加”后4 - 5小时出现的鸟氨酸脱羧酶活性增加，在添加血清前30分钟将培养基中Mg²⁺离子浓度增加30mM而不是Na⁺或K⁺离子浓度增加时，会显著降低，并且这种抑制至少维持24小时。在添加血清前30分钟向血清剥夺的培养物中添加甲基乙二醛双（脒腙）至浓度为20μM，严重抑制细胞生长的增加。同时向培养基中添加亚精胺（至100μM）可防止该药物的抑制作用，同时添加Mg²⁺离子（至30mM）可部分防止。Mg²⁺离子在克服甲基乙二醛双（脒腙）对DNA合成的抑制作用方面特别有效。因此，尽管BHK - 21/C13细胞中对阳离子存在一定程度的非特异性，即Mg²⁺离子在一定程度上可以替代多胺，特别是亚精胺，但存在一些细胞过程，对于这些过程，对多胺作为阳离子的需求是特异性的。
