Emmons C
Departments of Internal Medicine, University of Cincinnati and Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio 45267-0585, USA.
Am J Physiol. 1999 Apr;276(4):F635-43. doi: 10.1152/ajprenal.1999.276.4.F635.
To functionally characterize transport properties of the apical anion exchanger of rabbit beta-intercalated cells, the mean change in anion exchange activity, dpHi/dt (where pHi is intracellular pH), was measured in response to lumen Cl- replacement with gluconate in perfused cortical collecting ducts (CCDs). beta-Cell apical anion exchange was not affected by 15-min exposure to 0.2 mM lumen DIDS in the presence of 115 mM Cl-. In contrast, apical anion exchange was significantly inhibited by 0.1 mM lumen DIDS in the absence of Cl-. beta-Cell apical anion exchange was unchanged by 15 mM maleic anhydride, 10 mM phenylglyoxal, 0.2 mM niflumic acid, 1 mM edecrin, 1 mM furosemide, 1 mM probenecid, or 0.1 mM diphenylamine-2-carboxylate. However, beta-cell apical anion exchange was inhibited by alpha-cyano-4-hydroxycinnamic acid, with an IC50 of 2.4 mM. Substitution of either sulfate or gluconate for lumen Cl- resulted in a similar rate of alkalinization. Conversely, pHi was unchanged by substitution of sulfate for lumen gluconate, confirming the lack of transport of sulfate on the beta-cell apical anion exchanger. Taken together, the results demonstrate a distinct "fingerprint" of the rabbit CCD beta-cell apical anion exchanger that is unlike that of other known anion exchangers.
为了从功能上表征兔β-闰细胞顶端阴离子交换器的转运特性，在灌注的皮质集合管（CCD）中，用葡萄糖酸盐替代管腔Cl-，测量阴离子交换活性的平均变化，即dpHi/dt（其中pHi为细胞内pH）。在115 mM Cl-存在的情况下，β-细胞顶端阴离子交换不受0.2 mM管腔DIDS处理15分钟的影响。相反，在无Cl-的情况下，顶端阴离子交换受到0.1 mM管腔DIDS的显著抑制。15 mM马来酸酐、10 mM苯乙二醛、0.2 mM氟尼酸、1 mM依地尼酸、1 mM速尿、1 mM丙磺舒或0.1 mM二苯胺-2-羧酸盐对β-细胞顶端阴离子交换无影响。然而，α-氰基-4-羟基肉桂酸抑制β-细胞顶端阴离子交换，IC50为2.4 mM。用硫酸盐或葡萄糖酸盐替代管腔Cl-导致类似的碱化速率。相反，用硫酸盐替代管腔葡萄糖酸盐时pHi不变，证实了β-细胞顶端阴离子交换器上不存在硫酸盐转运。综上所述，结果表明兔CCDβ-细胞顶端阴离子交换器具有独特的“指纹”，与其他已知的阴离子交换器不同。
