Ozawa T, Saito Y, Nishiyama A
Department of Physiology, Tohoku University School of Medicine, Sendai, Japan.
J Membr Biol. 1988 Nov;105(3):273-80. doi: 10.1007/BF01871004.
Anion exchange transport in the mouse lacrimal gland acinar cell membrane was studied by measuring the intracellular H+ (pHi) and Cl- (aCli) activities with double-barreled ion-selective microelectrodes. In a HCO3- -free solution of pH 7.4 (HEPES/Tris buffered), pHi was 7.25 and aCli was 33 mM. By an exposure to a HCO3- (25 mM HCO3-/5% CO2, pH 7.4) solution for 15 min, aCli was decreased to 25 mM, and pHi was transiently decreased to about 7.05 within 1 min, then slowly relaxed to 7.18 in 15 min. Intracellular HCO3- concentration [HCO3-]i, calculated by the Henderson-Hasselbalch's equation, was 11 mM at 1 min after the exposure and then slowly increased to 15 mM. Readmission of the HCO3(-)-free solution reversed the changes in aCli and pHi. The intracellular buffering power was about 40 mM/pH. An addition of DIDS (0.2 mM) significantly inhibited the rates of change in aCli, pHi, and [HCO3-]i caused by admission/withdrawal of the HCO3- solution and decreased the buffer value. Replacement of all Cl- with gluconate in the HCO3- solution increased pHi, and readmission of Cl- decreased pHi. The rates of these changes in pHi were reduced by DIDS by 32-45% but not by amiloride (0.3 mM). In the HCO3- solution, a stimulation of intracellular HCO3- production by exposing the tissue to 25 mM NH4+ increased aCli significantly. While in the HCO3(-)-free solution or in the HCO3- solution containing DIDS, exposure to NH4+ had little effect on aCli.(ABSTRACT TRUNCATED AT 250 WORDS)
通过使用双管离子选择性微电极测量细胞内H⁺（pHi）和Cl⁻（aCli）活性，研究了小鼠泪腺腺泡细胞膜中的阴离子交换转运。在pH 7.4的无HCO₃⁻溶液（HEPES/Tris缓冲）中，pHi为7.25，aCli为33 mM。将其暴露于含HCO₃⁻（25 mM HCO₃⁻/5% CO₂，pH 7.4）的溶液中15分钟后，aCli降至25 mM，pHi在1分钟内短暂降至约7.05，然后在15分钟内缓慢回升至7.18。根据亨德森 - 哈塞尔巴尔赫方程计算，暴露1分钟后细胞内HCO₃⁻浓度[HCO₃⁻]i为11 mM，然后缓慢升至15 mM。重新加入无HCO₃⁻溶液可逆转aCli和pHi的变化。细胞内缓冲能力约为40 mM/pH。添加DIDS（0.2 mM）显著抑制了由加入/撤出HCO₃⁻溶液引起的aCli、pHi和[HCO₃⁻]i的变化速率，并降低了缓冲值。在HCO₃⁻溶液中用葡萄糖酸盐替代所有Cl⁻会使pHi升高，重新加入Cl⁻会使pHi降低。DIDS使这些pHi变化速率降低了32 - 45%，但amiloride（0.3 mM）无此作用。在HCO₃⁻溶液中，将组织暴露于25 mM NH₄⁺刺激细胞内HCO₃⁻产生，显著增加了aCli。而在无HCO₃⁻溶液或含DIDS的HCO₃⁻溶液中，暴露于NH₄⁺对aCli影响很小。（摘要截短于250字）
