NACL TRANSPORT IN MOUSE MEDULLARY THICK ASCENDING LIMBS .1. FUNCTIONAL NEPHRON HETEROGENEITY AND ADH-STIMULATED NACL COTRANSPORT
NACL TRANSPORT IN MOUSE MEDULLARY THICK ASCENDING LIMBS .1. FUNCTIONAL NEPHRON HETEROGENEITY AND ADH-STIMULATED NACL COTRANSPORT
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DOI：
10.1152/ajprenal.1981.241.4.f412
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发表时间：
1981-01-01
影响因子：
--
通讯作者：
ANDREOLI, TE
中科院分区：
文献类型：
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作者：
HEBERT, SC;CULPEPPER, RM;ANDREOLI, TE
我们评估了抗利尿激素和环磷酸腺苷(CAMP)类似物对小鼠离体延髓(MTALH)和皮质(CTALH)厚升支跨上皮电压、Ve和/或净氯吸收的影响；mTALH的被动氯化钠通透性特征和电学特性；以及阴阳离子取代和转运抑制剂对基础和ADH刺激的mTALH和/或净氯吸收的影响。数据表明，这两个部分在功能上是不同的：ADH的浓度与哺乳动物在普通抗利尿期间的血浆水平相当，和/或cAMP使mTALH对氯化钠的吸收速度增加三到四倍，而cTALH不增加。离子替代和抑制剂数据与NaC l在mTALH中的吸收依赖于二次主动转运过程的观点一致：NaC l跨腔膜进入是一个不确定化学计量比的耦合过程，该过程是由Na+-K+-ATPase维持的跨膜电化学梯度驱动的。最后，数据表明mTALH是电漏的，不管是电学测量，还是11欧米伽。Cm2，或同位素，50欧米伽。Cm2，但基本上不透水；mTALH对Na+相对于Cl-具有渗透选择性。直接测量的电阻与由示踪剂通量计算的电阻之间的差异，以及mTALH连接络合物的混合特性(对Na+和Cl-泄漏；对水紧密)，可以通过假设mTALH连接络合物包含由离子以单列方式通过的窄通道组成的被动离子渗透路径来协调。
We assessed the effects of antidiuretic hormone and cyclic adenosine monophosphate (cAMP) analogues on transepithelial voltage, Ve, and/or net chloride absorption in isolated mouse medullary (mTALH) and cortical (cTALH) thick ascending limbs of Henle; the passive NaCl permeability characteristics and electrical properties of the mTALH; and the effects of anion and cation substitutions and transport inhibitors on both basal and ADH-stimulated Ve and/or net chloride absorption in the mTALH. The data demonstrate that these two segments are functionally heterogeneous: ADH, at concentrations comparable to plasma levels seen in mammalian species during ordinary antidiuresis, and/or cAMP increase three- to fourfold the rate of NaCl absorption in the mTALH but not in the cTALH. The ion substitution and inhibitor data are consistent with the view that NaCl absorption in the mTALH depends on a secondary active transport process: NaCl entry across luminal membranes is a coupled process of indeterminate stoichiometry that is driven by the transmembrane electrochemical gradient for Na+, which is maintained by Na+-K+-ATPase. Finally, the data demonstrate that the mTALH is electrically leaky whether measured electrically, 11 omega . cm2, or isotopically, 50 omega . cm2, but essentially water impermeable; and that the mTALH is perm-selective for Na+ with respect to Cl-. The disparity between electrical resistances measured directly with respect to those calculated from tracer fluxes, together with the hybrid characteristics of mTALH junctional complexes (leaky to Na+ and Cl-; tight to water), may be reconciled by assuming that mTALH junctional complexes contain passive ion permeation pathways composed of narrow channels through which ions pass in single-file fashion.