Fluid absorption and active and passive ion flows in the rabbit superficial pars recta.
Fluid absorption and active and passive ion flows in the rabbit superficial pars recta.
复制标题
兔子浅部直肠中的液体吸收以及主动和被动离子流。
DOI：
10.1152/ajprenal.1977.233.2.f154
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
T. E. Andreoli
中科院分区：
文献类型：
--
作者：
J. A. Schafer;C. Patlak;T. E. Andreoli
用含有127.8 mM NaCl和3.8 mM NaHCO 3（pH 6.6）的Krebs-Ringer缓冲液灌注分离的兔近端直小管，并用含有105 mM NaCl和25 mM NaHCO 3（pH 7.4）的Krebs-Ringer缓冲液浸泡。在两种介质中，羟乙基磺酸钠代替乙酸钠;乙酸盐省略对净体积吸收（J V，nl min-1 mm-1）没有影响。在无醋酸盐培养基中，37°C时的J V为0.41 ± 0.04（SE），21°C时为0.16 ± 0.01。21°C时的J V值对被动驱动力的响应较小。37°C时跨上皮电压为+2.7 mV（管腔正），21°C时升高至+3.7 mV。在37°C时，净氯离子吸收量占净阳离子吸收量的85 ± 3%。数据进行了分析，在模型计算与流动扩散方程的横向细胞间隙。在37°C时，大约三分之一的Na +吸收可以通过耗散传输过程来解释;其余的是活性的。计算出的离子浓度沿着整个长度的细胞间隙几乎相同的离子浓度在洗澡解决方案，和被动离子运输上皮细胞准确预测从体相离子浓度。由于细胞间隙与外部溶液等体积，液体吸收可以用跨连接复合物的Cl -和HCO 3 -的相反方向梯度来解释，因为连接复合物对Cl -的渗透性比HCO 3 -更强。
Isolated rabbit proximal straight tubules were perfused with Krebs-Ringer buffers containing 127.8 mM NaCl and 3.8 mM NaHCO 3 (pH 6.6), and bathed with Krebs-Ringer buffers containing 105 mM NaCl and 25 mM NaHCO 3 (pH 7.4). Na isethionate replaced Na acetate in both mediums; acetate omission had no effect on net volume absorption (J V , nl min -1 mm -1 ). In acetate-free mediums, J V was 0.41 ± 0.04 (SE) at 37°C and 0.16 ± 0.01 at 21°C. J V at 21°C was referable to passive driving forces. The transepithelial voltage was +2.7 mV (lumen positive) at 37°C and rose to +3.7 mV at 21°C. At 37°C, net Cl - absorption accounted for 85 ± 3% of net cation absorption. The data were analyzed in terms of model calculations with flow-diffusion equations for lateral intercellular spaces. Approximately one-third of the Na + absorption at 37°C could be accounted for by dissipative transport processes; the remainder was active. The computed ionic concentrations along the entire length of intercellular spaces were nearly identical to the ionic concentrations in the bathing solutions, and passive ion transport across the epithelium was accurately predicted from bulk phase ion concentrations. With intercellular spaces isosomotic to the external solutions, fluid absorption could be accounted for in terms of the oppositely directed gradients of Cl - and HCO 3 - across junctional complexes, because the junctional complexes were more permeable to Cl - than HCO 3 - .