Swallow C J, Grinstein S, Sudsbury R A, Rotstein O D
Department of Surgery, Toronto General Hospital, Ontario, Canada.
Surgery. 1990 Aug;108(2):363-8; discussion 368-9.
Within the acidic milieu of an abscess or tumor, macrophages must be able to maintain their cytoplasmic pH (pHi) close to the physiologic range to ensure optimal cell function. Our recent studies have demonstrated that a proton-extrusion mechanism with the characteristics of an H+ adenosine triphosphatase mediates pHi recovery in acid-loaded macrophages. These studies were designed to examine the role of these H+ pumps in maintaining cell function in an acidic extracellular environment. Peritoneal macrophages were tested for superoxide production in response to phorbol myristate acetate at either physiologic or acidic extracellular pH (pHo; 7.35 or 6.70, respectively). pHi was measured with the fluorescent dye 2',7'-biscarboxy-ethyl-5(6)-carboxy-fluorescein. Bafilomycin A1, a specific H+ adenosine triphosphatase inhibitor, was used to examine the contribution of the H+ pump to pHi regulation and cell function. At pHo 7.35, bafilomycin A1 had no effect on pHi or phorbol myristate acetate-stimulated superoxide production. However, at pHo 6.70, bafilomycin A1 reduced pHi to 6.61 +/- 0.01 versus 6.79 +/- 0.01 in control cells (p less than 0.001) and caused a concomitant reduction in superoxide production to 4.8 +/- 1.2 versus 13.0 +/- 1.2 nmol/10(6) cells/40 min in control cells (p less than 0.001). To determine whether the observed reduction in superoxide formation was the result of the pHi reduction, superoxide production was measured in cells whose pHi was pharmacologically clamped at various levels according to the K+/nigericin method. Lowering pHi from 6.80 to 6.60 caused a significant reduction in superoxide production from 13.1 +/- 1.8 to 7.5 +/- 0.9 nmol/10(6) cells/40 min (p less than 0.01). Thus H+ extrusion pumps are important to maintenance of macrophage pHi at low pHo, permitting continued superoxide production under these conditions. By keeping pHi close to the physiologic range, these pumps serve to optimize cell function in an acidic extracellular environment.
在脓肿或肿瘤的酸性环境中，巨噬细胞必须能够将其细胞质pH值（pHi）维持在接近生理范围，以确保细胞功能的最佳状态。我们最近的研究表明，一种具有H⁺三磷酸腺苷酶特征的质子外排机制介导了酸负荷巨噬细胞中pHi的恢复。这些研究旨在探讨这些H⁺泵在酸性细胞外环境中维持细胞功能的作用。检测了腹腔巨噬细胞在生理或酸性细胞外pH值（pHo；分别为7.35或6.70）下对佛波酯肉豆蔻酸酯的超氧化物产生情况。用荧光染料2',7'-双羧乙基-5(6)-羧基荧光素测量pHi。使用特异性H⁺三磷酸腺苷酶抑制剂巴弗洛霉素A1来研究H⁺泵对pHi调节和细胞功能的作用。在pHo 7.35时，巴弗洛霉素A1对pHi或佛波酯肉豆蔻酸酯刺激的超氧化物产生没有影响。然而，在pHo 6.70时，巴弗洛霉素A1将pHi降至6.61±0.01，而对照细胞为6.79±0.01（p<0.001），并导致超氧化物产生随之减少，对照细胞为13.0±1.2，处理后为4.8±1.2 nmol/10⁶细胞/40分钟（p<0.001）。为了确定观察到的超氧化物形成减少是否是pHi降低的结果，根据K⁺/尼日利亚菌素法在药理学上使pHi维持在不同水平的细胞中测量超氧化物产生。将pHi从6.80降至6.60导致超氧化物产生从13.1±1.8显著减少至7.5±0.9 nmol/10⁶细胞/40分钟（p<0.01）。因此，H⁺外排泵对于在低pHo下维持巨噬细胞pHi很重要，使这些条件下能够持续产生超氧化物。通过使pHi接近生理范围，这些泵有助于在酸性细胞外环境中优化细胞功能。
