Axial heterogeneity of potassium transport across hamster thick ascending limb of Henle's loop.
Axial heterogeneity of potassium transport across hamster thick ascending limb of Henle's loop.
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穿过仓鼠亨利氏袢粗升肢的钾转运的轴向异质性。
DOI：
10.1152/ajprenal.1994.267.1.f121
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
M. Imai
中科院分区：
文献类型：
--
作者：
S. Tsuruoka;C. Koseki;S. Muto;K. Tabei;M. Imai
采用离体微灌注技术，探讨了仓鼠亨利氏袢粗升支沿着形态不均一性的功能意义，特别是对K+转运的影响。透射电镜观察证实，延髓粗升支（MTAL）内有表面光滑的细胞（S-细胞）和表面粗糙的细胞（R-细胞），而皮质部（CTAL）内则有表面粗糙的细胞。电生理研究表明，在这两个部分有两个细胞群体，一个具有高基底外侧和低顶端膜K+电导（HBC）和其他具有低基底外侧和高顶端K+电导（LBC）。随机细胞穿刺结果显示，MTAL中HBC/LBC的比例为24/7（77%/23%），CTAL中为7/22（24%/76%），提示HBC对应于S细胞，而LBC对应于R细胞。净K+运输确定在两个部分通过测量K+浓度的收集和灌注液中的超微火焰光度法。在MTAL的所有6个小管中，净K+通量具有重吸收方向，平均值为4.87 +/- 0.46 pmol.min-1.mm-1。与此形成鲜明对比的是，在CTAL的所有六个小管中，我们观察到K+分泌，平均值为-3.81 +/- 0.49 pmol.min-1.mm-1。两个节段的跨壁电压均为正，CTAL（7.8 +/- 0.5 mV）显著高于MTAL（2.5 +/- 0.2 mV）。根据这些观察，我们得出结论，对应于HBC细胞的S-细胞重吸收K+，而对应于LBC细胞的R-细胞分泌K+。（250字处删节）
Functional significance of morphological heterogeneities along the thick ascending limb of Henle's loop of hamsters was explored by the in vitro microperfusion technique with special reference to K+ transport. The transmission electron microscopic study confirmed that there are two types of cells, with smooth surface (S-cell) and rough surface (R-cell), respectively, and that the former is abundant in the medullary thick ascending limb (MTAL), whereas the latter is in the cortical portion (CTAL). The electrophysiological study revealed that in both segments there are two cell populations, one having high basolateral and low apical membrane K+ conductances (HBC) and the other having low basolateral and high apical K+ conductances (LBC). Random cell puncture revealed that the ratios of HBC/LBC were 24/7 (77%/23%) in the MTAL and 7/22 (24%/76%) in the CTAL, suggesting that HBC corresponds to S-cell, whereas LBC corresponds to R-cell. Net K+ transport was determined in two segments by measuring K+ concentration in the collected and perfused fluid by ultramicroflame photometry. In all six tubules of MTAL, net K+ flux had a direction to reabsorption with a mean of 4.87 +/- 0.46 pmol.min-1.mm-1. In marked contrast, in all six tubules of CTAL, we observed K+ secretion with a mean of -3.81 +/- 0.49 pmol.min-1.mm-1. The transmural voltage was positive in both segments and was significantly higher in the CTAL (7.8 +/- 0.5 mV) than in the MTAL (2.5 +/- 0.2 mV). From these observations, we conclude that the S-cell corresponding to the HBC cell reabsorbs K+, whereas the R-cell corresponding to the LBC cell secrets K+.(ABSTRACT TRUNCATED AT 250 WORDS)