Osmotic reflextion coefficients of capillary walls to low molecular weight hydrophilic solutes measured in single perfused capillaries of the frog mesentery.
Osmotic reflextion coefficients of capillary walls to low molecular weight hydrophilic solutes measured in single perfused capillaries of the frog mesentery.
复制标题
在青蛙肠系膜的单个灌注毛细血管中测量毛细血管壁对低分子量亲水性溶质的渗透反射系数。
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
J. C. Mason
中科院分区：
文献类型：
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作者：
F. Curry;C. Michel;J. C. Mason
1. 经透光处理的青蛙肠系膜的单个毛细血管中灌注了人红细胞悬浮液，该悬浮液中含有100毫升1 - 0克白蛋白。肠系膜外表面用正常的青蛙林格液和加入以下溶质之一的高渗青蛙林格液清洗：氯化钠（100 m - mol）。1 .量1);尿素（100 m - mol .1 - 1）；蔗糖（20 - 50 m - mol）1 .量1);氰钴胺素（8 - 5 m - mol）1 . 1)。所有实验中，肠系膜的温度都在14 ~ 16℃之间。2. 将肠系膜灌注正常的林格氏液后，在一系列已知的毛细管压力下，通过测量液体通过毛细血管壁的过滤速率来确定过滤系数（Michel, Mason, Curry & Tooke, 1974）。过滤系数从0‐69 × 10（‐3）到4‐45 × 10（‐3）之间变化。秒1。cm H2O‐1，平均值为1‐87 × 10（‐3）mum。秒1。厘米水1。3. 当加入试验溶质使过浓液呈高渗状态时，根据过滤的附加速率、过浓液中试验溶质的浓度和过滤系数计算毛细管壁对试验溶质的渗透反射系数（sigma）。sigma的平均值为：氯化钠，0‐068 +/‐0‐03（3根毛细血管）；尿素，0‐071 +/‐0.015（四根毛细血管）；蔗糖，0‐115 +/‐0‐023（7根毛细血管）；氰钴胺素，0‐100 +/‐0‐03（三根毛细血管）。4. 在进一步的实验中，测定了同一毛细管中对氯化钠、尿素和蔗糖的渗透反射系数。进行了五项技术上可接受的实验。虽然不同毛细管之间的sigma值存在差异，但在任何一个毛细管中，sigma值的大小都是相同的，并且与测试溶质的分子大小没有明显的趋势。5. 我们的发现与水和小亲水分子穿过毛细血管壁的单一途径的假设不一致。6. 我们的研究结果可以解释为水的独占通道与水和小亲水分子共享的通道平行。提示内皮细胞的排他性水通道可能位于细胞膜和细胞质内，而共享水通道可能位于细胞间连接处。7. 我们的数据表明，在青蛙肠系膜毛细血管中，排他的水通道约占总过滤系数的10%。共享通道对所研究的分子显示出相对较小的限制。在流体静压差和渗透压差为驱动力的条件下，对通过这两个通道的体积流量进行了估计。
1. Individual capillaries of the transilluminated frog mesentery have been perfused with suspensions of human red cells in frog Ringer solution containing 1‐0 g albumin 100 ml.‐1. The outer surface of the mesentery has been washed with normal frog Ringer solution and with frog Ringer solutions made hypertonic by addition of one of the following solutes: sodium chloride (100 m‐mole. 1.‐1); urea (100 m‐mole.1.‐1); sucrose (20‐50 m‐mole. 1.‐1); cyanocobalamin (8‐5 m‐mole. 1.‐1). The temperature of the mesentery was between 14 and 16 degrees C in all experiments. 2. Wtih the mesentery superfused with normal Ringer, the filtration coefficient was determined from measurements of the rate of fluid filtration across the capillary wall, at a series of known capillary pressures (Michel, Mason, Curry & Tooke, 1974). Filtration coefficient varied from 0‐69 X 10(‐3) to 4‐45 X 10(‐3) mum. sec‐1 .cm H2O‐1 with an average value of 1‐87 X 10(‐3) mum. sec‐1. cm H2O‐1. 3. When the superfusate was made hypertonic by the addition of a test solute, the osmotic reflextion coefficient (sigma) of the capillary wall to test solute was calculated from the additional rate of filtration, the concentration of test solute in the superfusate and the filtration coefficient. Average values for sigma were: sodium chloride, 0‐068 +/‐ 0‐03 (three capillaries); urea, 0‐071 +/‐ 0.015 (four capillaries); sucrose, 0‐115 +/‐ 0‐023 (seven capillaries); cyanocobalamin, 0‐100 +/‐ 0‐03 (three capillaries). 4. In further experiments, the osmotic reflextion coefficients to sodium chloride, urea and sucrose were determined in the same capillary. Five technically acceptable experiments were carried out. Although there were differences in the value of sigma between different capillaries, in any one capillary values of sigma were of the same magnitude and there appeared to be no significant trend with the molecular size of the test solute. 5. Our findings are inconsistent with the hypothesis that there is a single pathway for water and small hydrophilic molecules across the capillary wall. 6. Our results may be interpreted in terms of an exclusive channel for water in parallel with a channel shared by both water and small hydrophilic molecules. It is suggested that the exclusive water channel may be the membranes and cytoplasm of the endothelial cells and the shared channel may be located in the intercellular junctions. 7. Our data suggest the exclusive water channel represents about 10% of the total filtration coefficient in frog mesenteric capillaries. The shared channel shows relatively little restriction to the molecules investigated. Estimates of the volume flow throught the two channels are made for conditions where hydrostatic pressure differences and osmotic pressure differences are the driving forces.