NaCl transport in mouse medullary thick ascending limbs. III. Modulation of the ADH effect by peritubular osmolality.
NaCl transport in mouse medullary thick ascending limbs. III. Modulation of the ADH effect by peritubular osmolality.
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小鼠髓质厚升肢中的 NaCl 转运。
DOI：
10.1152/ajprenal.1981.241.4.f443
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Andreoli,TE
中科院分区：
文献类型：
--
作者：
Hebert,SC;Culpepper,RM;Andreoli,TE
我们评估了增加浴渗透压对被动渗透性能和ADH依赖性的净Cl-吸收率在离体小鼠髓厚的汉勒升支（mTALH）的影响。用600 mM尿素将两种渗透压摩尔浓度增加至900 mosmol/kg H2O，对电（PNa/PCl比，分别为1.7和1.9，有和没有管周尿素）或示踪剂（PNa，0.21和0.22微米。s-1，分别有和没有管周尿素）的mTALH的离子渗透性特征。然而，这种程度的尿素浴高渗性可逆地降低了JnetNaCl，跨上皮NaCl吸收的净速率，和Ve，自发跨上皮电压：JnetNaCl下降了85%，Ve下降了70%。这两种后一种效应都可以通过tau NaCl（保守的跨细胞NaCl转运速率）减少85%来定量解释。Ve的抑制肾小管周围介质尿素高渗性不改变由超最大浴浓度的ADH，超最大浴浓度的cAMP类似物，或对称添加尿素灌注液和浴。肾小管周围介质甘露醇浓度的增加也降低了Ve; Ve的抑制作用不会被aDH的最大浴浓度逆转。细胞体积与管周尿素保持不变，但减少管周甘露醇。这些数据表明，在mTALH增加浴渗透压与非电解质抑制tau NaCl非竞争性ADH或cAMP和独立的细胞体积。JnetCl也减少与管周介质NaCl浓度的增加，并与细胞体积的减少。
We evaluated the effects of increasing bath osmolality on both the passive permeability properties and the ADH-dependent rates of net Cl- absorption in isolated mouse medullary thick ascending limbs of Henle (mTALH). Increases in both osmolality to 900 mosmol/kg H2O with 600 mM urea had no effect on either the electrical (PNa/PCl ratio, 1.7 and 1.9 with and without peritubular urea, respectively) or tracer (PNa, 0.21 and 0.22 micrometers . s-1 with and without peritubular urea, respectively) ionic permeability characteristics of the mTALH. However, this degree of urea bath hypertonicity reduced reversibly both JnetNaCl, the net rate of transepithelial NaCl absorption, and Ve, the spontaneous transepithelial voltage: JnetNaCl fell by 85% and Ve by 70%. Both of these latter effects could be accounted for quantitatively by an 85% reduction in tau NaCl, the rate of conservative transcellular NaCl transport. The inhibition of Ve by peritubular medium urea hypertonicity was not altered by supramaximal bath concentrations of ADH, supramaximal bath concentrations of cAMP analogues, or symmetrical addition of urea to perfusate and bath. Increases in peritubular medium mannitol concentrations also reduced Ve; the inhibition of Ve was not reversed by supramaximal bath concentrations of aDH. Cell volume remained unchanged with peritubular urea but was reduced by peritubular mannitol. These data indicate that in the mTALH increases in bath osmolality with nonelectrolytes inhibit tau NaCl noncompetitively with respect to ADH or cAMP and independently of cell volume. JnetCl was also reduced with increases in peritubular medium NaCl concentration and was associated with a reduction in cell volume.