Gillespie J I, Hedley C, Greenwell J R, Argent B E
Department of Physiological Sciences, University Medical School, Newcastle upon Tyne.
Q J Exp Physiol. 1989 Nov;74(6):883-95. doi: 10.1113/expphysiol.1989.sp003359.
We have measured the intracellular pH (pHi) of single isolated rat pancreatic acini using the fluorescent dye dicyano-hydroquinone (DCH). Steady-state pHi was unaffected by either acetylcholine (10 microM), caerulein (10 nM) or secretin (1 nM), or by the anion exchange inhibitor DIDS (1 mM) and only changed by 0.32 units when extracellular pH was varied over the range from 6.8 to 8.4. However, replacing extracellular chloride with gluconate, such that the final bath chloride concentration was less than 20 mM, caused a marked alkalinization of pHi to a new steady-state value. The rate of pHi alkalinization under these conditions was bicarbonate-dependent, blocked by pre-incubation of the acini with 1 mM-DIDS, but unaffected by removal of extracellular sodium. These observations are consistent with the presence of a Cl- -HCO3- exchanger on rat pancreatic acinar cells. Since DIDS had no effect on steady-state pHi the anion exchanger is unlikely to play a role in pHi regulation. However, rat pancreatic acini secrete a NaCl-rich fluid and the Cl- -HCO3- a exchanger might function in parallel with Na+-H+ exchangers to provide a mechanism for chloride accumulation across the basolateral membrane of the acinar cells.
我们使用荧光染料二氰基对苯二酚（DCH）测量了单个分离的大鼠胰腺腺泡的细胞内pH值（pHi）。稳态pHi不受乙酰胆碱（10微摩尔）、蛙皮素（10纳摩尔）或促胰液素（1纳摩尔）的影响，也不受阴离子交换抑制剂二异丁基氨磺酰苯甲酸盐（DIDS，1毫摩尔）的影响，并且当细胞外pH值在6.8至8.4范围内变化时，pHi仅改变0.32个单位。然而，用葡萄糖酸盐替代细胞外氯离子，使得最终浴液中的氯离子浓度低于20毫摩尔，会导致pHi显著碱化至新的稳态值。在这些条件下，pHi碱化的速率依赖于碳酸氢盐，在腺泡用1毫摩尔DIDS预孵育后受到阻断，但不受细胞外钠离子去除的影响。这些观察结果与大鼠胰腺腺泡细胞上存在氯离子-碳酸氢根交换体一致。由于DIDS对稳态pHi没有影响，阴离子交换体不太可能在pHi调节中发挥作用。然而，大鼠胰腺腺泡分泌富含氯化钠的液体，氯离子-碳酸氢根交换体可能与钠离子-氢离子交换体并行发挥作用，为氯离子在腺泡细胞基底外侧膜上的积累提供一种机制。
