Apical proton secretion by the inner stripe of the outer medullary collecting duct.
Apical proton secretion by the inner stripe of the outer medullary collecting duct.
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顶端质子由外髓集合管的内条纹分泌。
DOI：
10.1152/ajprenal.1999.276.4.f606
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Wingo,CS
中科院分区：
文献类型：
--
作者：
Weiner,ID;Frank,AE;Wingo,CS
外髓收集管（OMCDis）的内条纹在收集管段中是独特的，因为插入细胞和主细胞都分泌质子并重新吸收腔内碳酸氢盐。本研究明确了omc二质子分泌的机制。我们采用体外微灌注，分别研究了主细胞和插层细胞，使用不同的荧光，ph敏感染料，2 ',7 ' -双（2-羧基乙基）-5(6)-羧基荧光素（BCECF）。主细胞和插入细胞都分泌质子，被鉴定为从细胞内酸负荷中恢复Na+/H+交换无关的细胞内pH （pHi）。在主细胞中发现了两个质子转运活动；一种是腔内钾依赖型，对Sch-28080敏感；另一种是腔内钾独立型，对腔内巴霉素a1敏感。因此，OMCDisprincipal细胞同时表达顶端H+-K+- atp酶和H+- atp酶活性。插入细胞Na+/H+交换无关的pHirecovery大约是主细胞的两倍，并且由类似的药理学机制介导。我们得出结论：1)omc2主细胞可能参与尿腔钾重吸收和尿液酸化，其作用与皮质集管中的主细胞有本质的不同；2) omc脱插细胞质子转运体在功能上与主细胞中的质子转运体相似，这表明与主细胞中存在的类似的H+-K+- atp酶可能有助于插入细胞的质子分泌。
The inner stripe of outer medullary collecting duct (OMCDis) is unique among collecting duct segments because both intercalated cells and principal cells secrete protons and reabsorb luminal bicarbonate. The current study characterized the mechanisms of OMCDisproton secretion. We used in vitro microperfusion, and we separately studied the principal cell and intercalated cell using differential uptake of the fluorescent, pH-sensitive dye, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Both the principal cell and intercalated cell secreted protons, as identified as Na+/H+exchange-independent intracellular pH (pHi) recovery from an intracellular acid load. Two proton transport activities were identified in the principal cell; one was luminal potassium dependent and Sch-28080 sensitive and the other was luminal potassium independent and luminal bafilomycin A1sensitive. Thus the OMCDisprincipal cell expresses both apical H+-K+-ATPase and H+-ATPase activity. Intercalated cell Na+/H+exchange-independent pHirecovery was approximately twice that of the principal cell and was mediated by pharmacologically similar mechanisms. We conclude1) the OMCDisprincipal cell may contribute to both luminal potassium reabsorption and urinary acidification, roles fundamentally different from those of the principal cell in the cortical collecting duct; and2) the OMCDisintercalated cell proton transporters are functionally similar to those in the principal cell, raising the possibility that an H+-K+-ATPase similar to the one present in the principal cell may contribute to intercalated cell proton secretion.