Chan Y L, Biagi B, Giebisch G
Am J Physiol. 1982 May;242(5):F532-43. doi: 10.1152/ajprenal.1982.242.5.F532.
Bicarbonate transport (JHCO3) was studied in rat proximal convoluted tubules by luminal and peritubular microperfusion, and the effects on tubular bicarbonate transport of selective changes in luminal and peritubular bicarbonate concentrations and of changes in luminal flow rate were evaluated. A pH glass electrode was used to measure [HCO3(-)] and gave results similar to those of a microcalorimetric method. Increasing the tubular and peritubular [HCO3(-)] at constant luminal perfusion rate (10 nl.min-1) augmented JHCO3, but JHCO3 increased more when pH changes were prevented by PCO2 adjustments (constant peritubular pH) than when pH was allowed to rise with the increase in [HCO3(-)] (constant PCO2). Elevation of the tubular HCO3(-) load by raising [HCO3(-)] stimulated JHCO3 more than when the HCO3(-) load was raised by enhancing luminal perfusion rate at constant [HCO3(-)] An increase in PCO2 at constant peritubular pH increased JHCO3. Diamox and benzolamide inhibited JHCO3 at luminal concentrations of 2-4 X 10(-4) M, yet a small but significant fraction of JHCO3 remained intact. Capillary perfusion with 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (5 X 10(-4) M) depressed JHCO3 by 70%. Acute changes in luminal and peritubular potassium concentrations (range, 2-6 meq/liter) had no effect on JHCO3, but JHCO3 increased moderately but significantly in severe dietary hypokalemia.
通过管腔和肾小管周围微灌注研究了大鼠近端曲管中的碳酸氢盐转运（JHCO3），并评估了管腔和肾小管周围碳酸氢盐浓度的选择性变化以及管腔流速变化对肾小管碳酸氢盐转运的影响。使用pH玻璃电极测量[HCO3(-)]，其结果与微量量热法的结果相似。在恒定管腔灌注速率（10 nl·min-1）下增加管腔和肾小管周围的[HCO3(-)]可增加JHCO3，但当通过PCO2调节防止pH变化（恒定肾小管周围pH）时，JHCO3的增加幅度大于当pH随[HCO3(-)]的增加而升高时（恒定PCO2）。通过提高[HCO3(-)]来增加管腔碳酸氢盐负荷比在恒定[HCO3(-)]下通过提高管腔灌注速率来增加碳酸氢盐负荷更能刺激JHCO3。在恒定肾小管周围pH下增加PCO2可增加JHCO3。二氮嗪和苯磺酰胺在管腔浓度为2 - 4×10(-4) M时抑制JHCO3，但仍有一小部分但显著的JHCO3保持完整。用4-乙酰氨基-4'-异硫氰基芪-2,2'-二磺酸（5×10(-4) M）进行毛细血管灌注可使JHCO3降低70%。管腔和肾小管周围钾浓度的急性变化（范围为2 -6 meq/升）对JHCO3没有影响，但在严重饮食性低钾血症中JHCO3适度但显著增加。
