Evidence for transcellular osmotic water flow in rat proximal tubules.
Evidence for transcellular osmotic water flow in rat proximal tubules.
复制标题
大鼠近曲小管跨细胞渗透水流的证据。
DOI：
10.1152/ajprenal.1985.249.1.f124
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Berry,CA
中科院分区：
文献类型：
--
作者：
Preisig,PA;Berry,CA
为了确定跨上皮渗透水流的主要途径，在体内微灌注的大鼠近曲小管中测定了跨上皮渗透水渗透性[Pf（TE）]和细胞旁孔和狭缝的表观尺寸。为了测量Pf（TE），用低渗含氰化物的溶液灌注小管。假设σ NaCl等于1.0-0.7，根据观察到的体积通量对测得的对数平均渗透梯度的响应计算的Pf（TE）分别为0.12-0.15 cm/s。使用测量的蔗糖和甘露醇渗透性（非电解质局限于细胞外空间）确定细胞旁途径的尺寸。它们分别为0.43和0.87 × 10（-5）cm/s。通过使用这些渗透率的比率、它们各自的自由溶液扩散系数和分子半径以及Renkin方程，计算出非电解质渗透孔的半径和总孔面积/cm 2表面积/通道长度分别为1.4 nm和3.56 cm-1。对狭缝的类似计算得到0.8 nm的狭缝半宽和3.16 cm-1的总狭缝面积/cm 2表面积/通道长度。这些非电解质渗透途径的渗透水渗透性通过Poiffuille定律计算为0.0018 cm/s（孔）或0.0014 cm/s（狭缝），至多为Pf（TE）的2%。我们的结论是，在紧密连接的非电解质渗透途径是不是在大鼠近端小管的跨上皮渗透水流的主要途径。
To determine the predominant pathway for transepithelial osmotic water flow, the transepithelial osmotic water permeability [Pf(TE)] and the apparent dimensions of paracellular pores and slits were determined in rat proximal convoluted tubules microperfused in vivo. To measure Pf(TE), tubules were perfused with a hyposmotic, cyanide-containing solution. Pf(TE), calculated from the observed volume flux in response to the measured log mean osmotic gradient, was 0.12-0.15 cm/s, assuming sigmaNaCl equal to 1.0-0.7, respectively. The dimensions of the paracellular pathways were determined using measured sucrose and mannitol permeabilities (nonelectrolytes confined to the extracellular space). These were 0.43 and 0.87 X 10(-5) cm/s, respectively. By using the ratio of these permeabilities, their respective free solution diffusion coefficients and molecular radii, and the Renkin equation, the radius of the nonelectrolyte-permeable pores and the total pore area/cm2 surface area/channel length were calculated to be 1.4 nm and 3.56 cm-1, respectively. Similar calculations for slits yielded a slit half-width of 0.8 nm and a total slit area/cm2 surface area/channel length of 3.16 cm-1. The osmotic water permeability of these nonelectrolyte-permeable pathways was calculated by Poiseuille's law to be 0.0018 cm/s (pores) or 0.0014 cm/s (slits), at most 2% of Pf(TE). We conclude that the nonelectrolyte-permeable pathway in the tight junctions is not the major route of transepithelial osmotic water flow in the rat proximal tubule.