Schneider M, Marison I W, von Stockar U
Institute of Chemical Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland.
J Biotechnol. 1996 May 15;46(3):161-85. doi: 10.1016/0168-1656(95)00196-4.
Ammonia has been reported to be toxic and inhibitory for mammalian cell cultures for many years. Reduction of growth rates and maximal cell densities in batch cultures, changes in metabolic rates, perturbation of protein processing and virus replication have been reported. However, cellular mechanisms of ammonia toxicity are still the subject of controversy and are presented here. The physical and chemical characteristics of ammonia and ammonium are important, with the former capable of readily diffusing across cellular membranes and the latter competing with other cations for active transport by means of carrier proteins. The main source of the ammonia which accumulates in cell cultures is glutamine, which plays an important role in the metabolism of rapidly growing cells. Strategies to overcome toxic ammonia accumulation include substitution of glutamine by glutamate or other amino acids, nutrient control, i.e., controlled addition of glutamine at low concentrations, or removal of ammonia or ammonium from the culture medium by means of ion-exchange resins, ion-exchange membranes, gas-permeable membranes or electrodialysis.
多年来，氨一直被报道对哺乳动物细胞培养有毒性并具有抑制作用。据报道，在分批培养中生长速率和最大细胞密度降低、代谢速率改变、蛋白质加工和病毒复制受到干扰。然而，氨毒性的细胞机制仍然存在争议，本文将对此进行阐述。氨和铵的物理化学特性很重要，前者能够轻易穿过细胞膜扩散，而后者则通过载体蛋白与其他阳离子竞争主动运输。细胞培养中积累的氨的主要来源是谷氨酰胺，它在快速生长细胞的代谢中起重要作用。克服有毒氨积累的策略包括用谷氨酸或其他氨基酸替代谷氨酰胺、营养控制，即低浓度控制添加谷氨酰胺，或通过离子交换树脂、离子交换膜、透气膜或电渗析从培养基中去除氨或铵。
