BICARBONATE TRANSPORT IN CORTICAL AND OUTER MEDULLARY COLLECTING TUBULES
BICARBONATE TRANSPORT IN CORTICAL AND OUTER MEDULLARY COLLECTING TUBULES
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DOI：
10.1152/ajprenal.1983.244.3.f289
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发表时间：
1983-01-01
影响因子：
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通讯作者：
JACOBSON, HR
中科院分区：
文献类型：
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作者：
LOMBARD, WE;KOKKO, JP;JACOBSON, HR
集合管被认为代表低容量高梯度酸化系统。集合管系统各个区域的不可接近性阻碍了对其对远端酸化的贡献进行直接分段分析。目前的体外微灌注研究比较了用 pH 7.4 的对称林格 HCO3- 溶液灌注和沐浴的兔皮质 (CCT) 和外髓集合管 (MCT) 中的 HCO3- 转运（每分钟 pmol/min）。正常动物的皮质节段没有表现出净碳酸氢盐运输（-2.15.+-.1.93）；正常动物的 MCT 以 11.3 .+- 的速率重吸收 HCO3-。 1.4. MCT 中的 HCO3- 重吸收和管腔正电压 (+9.4.+-.1.1 mV) 均被 10-4 M 乙酰唑酰胺完全抑制。 NH4Cl 处理的兔子的 CCT 显示，当以低速率灌注时，有显着的 HCO3- 重吸收 (1.8.+-.0.7)。从死亡前给予 NaHCO3 负载 48 小时的动物收获的 CCT 分泌 HCO3- (-6.2.+-.2.5)。证实了CCT重吸收或分泌HCO3-的能力。他们证明了集合管系统中酸化的显着轴向异质性，并将外髓集合管从外髓内条纹识别为主要容量的一部分。
The collecting ducts are thought to represent a low-capacity high-gradient acidification system. The inaccessibility of the various regions of the collecting duct system has prevented direct segmental analysis of its contribution to distal acidification. The present in vitro microperfusion studies compare HCO3- transport (in pmol/min per min) in rabbit cortical (CCT) and outer medullary collecting tubules (MCT) perfused and bathed with symmetrical Ringer HCO3- solution at pH 7.4. Cortical segments from normal animals exhibited no net bicarbonate transport (-2.15 .+-. 1.93); MCT from normal animals reabsorbed HCO3- at a rate of 11.3 .+-. 1.4. Both HCO3- reabsorption and the lumen-positive voltage (+9.4 .+-. 1.1 mV) in MCT were totally inhibited by 10-4 M acetazolamide. CCT from NH4Cl-treated rabbits demonstrated significant HCO3- reabsorption (1.8 .+-. 0.7) when perfused at slow rates. CCT harvested from animals given a NaHCO3 load for 48 h prior to death secreted HCO3- (-6.2 .+-. 2.5). The ability of the CCT to reabsorb or secrete HCO3- was confirmed. They demonstrate significant axial heterogeneity in acidification in the collecting duct system and identify the outer medullary collecting tubule from inner stripe of outer medulla as a segment of major capacity.