Orlinska U, Newton R C
Inflammatory Diseases Research, Du Pont Merck Pharmaceutical Co., Wilmington, DE 19880, USA.
Immunopharmacology. 1995 Jun;30(1):41-50. doi: 10.1016/0162-3109(95)00006-f.
Tumor necrosis factor-alpha (TNF-alpha) is produced and secreted from monocytes in response to activation with lipopolysaccharide (LPS). The role of Na+ and HCO3- in the production of TNF-alpha by monocytes was investigated; it was observed that replacement of Na+ in the culture medium with sucrose or choline chloride inhibited TNF-alpha production completely. The addition of Na+ to Na(+)-free culture medium restored TNF-alpha production with an EC50 value of 35 mmol/l. The amiloride analog 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of the Na+/H+ antiporter, inhibited TNF-alpha production with an EC50 of 3.3 microM. Without HCO3- in the culture medium TNF-alpha production was inhibited by 92%. Total protein synthesis was inhibited by 85% in the absence of Na+ but did not change in the absence of bicarbonate in the culture medium. Intracellular pH (pHi) which increased from 6.90 in control monocyte to 7.40 in response to activation with LPS was abrogated to pHi of 6.95 in the absence of Na+ but did not change in the absence of HCO3- in the culture medium. In the presence of 100 microM phloretin or DIDS the pHi of activated monocyte was reduced to control value, TNF-alpha production was inhibited completely and total protein synthesis was inhibited by 61%. These data suggest that (1) TNF-alpha production, as other proteins, is dependent on the pHi of monocytes,and (2) TNF-alpha production, in contrast to total protein, is modulated by Na(+)-dependent HCO3-.
肿瘤坏死因子-α（TNF-α）由单核细胞在脂多糖（LPS）激活后产生并分泌。研究了Na⁺和HCO₃⁻在单核细胞产生TNF-α过程中的作用；观察到用蔗糖或氯化胆碱替代培养基中的Na⁺可完全抑制TNF-α的产生。向无Na⁺的培养基中添加Na⁺可恢复TNF-α的产生，其半数有效浓度（EC50）值为35 mmol/L。钠氢交换体抑制剂阿米洛利类似物5-（N-乙基-N-异丙基）阿米洛利（EIPA）以3.3 μM的EC50抑制TNF-α的产生。培养基中无HCO₃⁻时，TNF-α的产生被抑制92%。在无Na⁺的情况下，总蛋白合成被抑制85%，但在培养基中无碳酸氢盐时总蛋白合成没有变化。细胞内pH（pHi）在LPS激活后从对照单核细胞中的6.90升高到7.40，在无Na⁺时被消除到6.95，但在培养基中无HCO₃⁻时没有变化。在存在100 μM根皮素或二异丙基氨基磺酸钠（DIDS）的情况下，激活的单核细胞的pHi降低到对照值，TNF-α的产生被完全抑制，总蛋白合成被抑制61%。这些数据表明：（1）TNF-α的产生与其他蛋白质一样，依赖于单核细胞的pHi；（2）与总蛋白相反，TNF-α的产生受Na⁺依赖性HCO₃⁻的调节。
