Bowen J W, Levinson C
J Cell Physiol. 1986 Jul;128(1):55-60. doi: 10.1002/jcp.1041280110.
The effect of changes in extracellular pH (pHo) and intracellular pH (pHi) on Na+-dependent and Na+-independent inorganic phosphate (Pi) transport in Ehrlich cells was investigated. In the presence of Na+, acutely reducing pHo from 7.30 to 5.50 results first in a transient (approximately 7 min) stimulation of Pi transport. The enhanced rate of transport is a saturable function of the extracellular [H+]; the Ks equals 2.3 X 10(-6) M (pHo 6.68). However, Pi transport is progressively inhibited as pHi falls below 6.50. The effect of pHi on Pi transport measured at various intracellular [Na+] suggests that inhibition develops as a consequence of H+ interaction with an intracellular Na+ site(s) on the Na+-dependent carrier. At pHo 7.4, about 15% of the steady state Pi flux persists in the absence of Na+. However, when pHo is reduced, transport is stimulated to the same extent and with the same time course and kinetic characteristics as in the presence of Na+. Thus, H+ stimulated Pi transport does not require Na+, raising the possibility that the Na+-independent component is mediated by the anion (Cl-) exchanger.
研究了细胞外pH值（pHo）和细胞内pH值（pHi）的变化对艾氏腹水癌细胞中钠依赖性和非钠依赖性无机磷酸盐（Pi）转运的影响。在有Na+存在的情况下，将pHo从7.30急剧降至5.50首先会导致Pi转运出现短暂（约7分钟）的刺激。转运速率的增强是细胞外[H+]的饱和函数；Ks等于2.3×10（-6）M（pHo 6.68）。然而，当pHi降至6.50以下时，Pi转运逐渐受到抑制。在不同细胞内[Na+]水平下测量pHi对Pi转运的影响表明，抑制作用的产生是由于H+与钠依赖性载体上的细胞内Na+位点相互作用的结果。在pHo 7.4时，约15%的稳态Pi通量在无Na+的情况下持续存在。然而，当pHo降低时，转运受到的刺激程度、时间进程和动力学特征与有Na+存在时相同。因此，H+刺激的Pi转运不需要Na+，这增加了非钠依赖性成分由阴离子（Cl-）交换体介导的可能性。
