Helgeland K
Scand J Dent Res. 1985 Feb;93(1):39-45. doi: 10.1111/j.1600-0722.1985.tb01306.x.
pH variations in the range from 6.9 to 7.9 modified the growth rate of human gingival fibroblasts in culture, a pH optimum being found at 7.6-7.8. A pH dependent growth inhibition by ammonia was evident, being particularly prominent in the presence of 2 mM NH4Cl. At this concentration an effect ranging from a complete cessation of growth at pH 8.0 to an indication of a slight stimulatory effect at pH 7.2 was found. Concomitant with this amplification of the growth inhibitory effect, a state of unbalanced growth in the sense of an increased cellular protein content was induced by ammonia upon increasing the pH of the medium. The incorporation of 14C-proline into the total protein fraction decreased rapidly, particularly in the control cultures, with pH; an inhibition by ammonia being found at pH 7.0 and 7.5 with no effect at pH 7.1. Except for part of the inhibition by ammonia, changes in specific activity of 14C-proline in the cellular amino acid pool could ac count for these pH effects. Ammonia reduced the proportion of radiolabeled protein recovered as collagen both from the cells and medium at the lower pHs, whereas the only significant effect on noncollagen protein was an increased fraction being secreted at pH 7.1 in the presence of 10 mM NH4Cl.
pH值在6.9至7.9范围内的变化会改变培养的人牙龈成纤维细胞的生长速率，最适宜的pH值为7.6 - 7.8。氨对生长的抑制作用明显依赖于pH值，在2 mM NH₄Cl存在时尤为显著。在此浓度下，发现其作用范围从pH 8.0时完全停止生长到pH 7.2时略有刺激作用。随着这种生长抑制作用的增强，随着培养基pH值升高，氨会诱导细胞蛋白质含量增加意义上的生长不平衡状态。14C - 脯氨酸掺入总蛋白部分的量迅速减少，尤其是在对照培养物中随pH值变化；在pH 7.0和7.5时发现氨有抑制作用，在pH 7.1时无影响。除了部分氨的抑制作用外，细胞氨基酸池中14C - 脯氨酸比活性的变化可以解释这些pH值效应。在较低pH值下，氨会降低从细胞和培养基中回收的作为胶原蛋白的放射性标记蛋白的比例，而在10 mM NH₄Cl存在时，对非胶原蛋白的唯一显著影响是在pH 7.1时分泌部分增加。
