STUDY OF CHLORIDE TRANSPORT ACROSS RABBIT CORTICAL COLLECTING TUBULE
STUDY OF CHLORIDE TRANSPORT ACROSS RABBIT CORTICAL COLLECTING TUBULE
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DOI：
10.1172/jci109111
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发表时间：
1978-01-01
影响因子：
15.9
通讯作者：
KOKKO, JP
中科院分区：
文献类型：
--
作者：
HANLEY, MJ;KOKKO, JP
集合小管可能参与细胞外液量的调节。Cl运输在体外灌注的兔皮质集合小管进行了评价，因为Cl-最终可能会影响细胞外液量。用模拟超滤液的人工溶液灌注和浸泡肾小管。进行了四组研究。在第1组和第2组中，将未接受脱氧皮质酮（DOCA）的家兔的肾小管与接受DOCA（5 mg/天）1周的家兔的肾小管进行比较。在第3组和第4组中，仅从未接受DOCA的家兔中获得肾小管。在第1组中，连续双向氯通量进行了测量。Cl流出量与流入量的比值为0.99 ± 0.01。0.04在得自未接受DOCA的兔的小管中，其为1.28 ±。0.09在从接受DOCA的家兔获得的小管中，表明在这些条件下刺激净Cl通量。在第2组中，测量收集的液体的化学Cl浓度和渗透压。在非DOCA处理的家兔的小管中，收集的液体的化学Cl浓度和渗透压均未显著降低至低于其各自的灌注液值，但在DOCA处理的家兔的小管中，收集的液体的化学Cl浓度（10-42 meq/l）和渗透压（10-42 mosmol/kg H2O）显著降低。在第3组中，单向氯渗透率从内腔浴测定电流下降的过程中的灌注移液管。平均管腔电位的变化，-35 . ±. 4 + 28.+-. 2 mV，不影响单向Cl运动，表明皮质集合小管对Cl是完全不可渗透的。在第4组中，单向氯渗透从内腔到浴之前和之后的NaCH 3SO 4替代NaCl浴。用CH 3SO 4置换Cl可逆地降低了表观Cl渗透率，从2.41 .+-. 0.50至0.69 . ±. 0.08. times. (10-5 cm/s），表明36 Cl渗透性取决于Cl的化学浓度。皮质集合小管能够重吸收盐循环盐皮质激素的调制下，因此，可能参与整体体积的稳态。皮质集合小管的Cl渗透性和同位素Cl通量的主要部分是通过交换扩散。在某些情况下，皮质集合小管可起稀释作用。
The collecting tubule may be involved in regulation of extracellular fluid volume. Cl transport across the in vitro-perfused rabbit cortical collecting tubule was evaluated inasmuch as Cl- ultimately may affect extracellular fluid volume. Tubules were perfused and bathed with artificial solutions simulating ultrafiltrate. Four groups of studies were conducted. In groups 1 and 2, tubules from rabbits not receiving deoxycorticosterone (DOCA) were compared to tubules from rabbits which had received DOCA (5 mg/day) for 1 wk. In groups 3 and 4, tubules were obtained only from rabbits not receiving DOCA. In group 1, sequential bidirectional Cl fluxes were measured. The ratio of Cl efflux to influx was 0.99 .+-. 0.04 in tubules obtained from rabbits not receiving DOCA, whereas it was 1.28 .+-. 0.09 in tubules obtained from rabbits receiving DOCA, suggesting stimulation of net Cl flux under these conditions. In group 2, chemical Cl concentration and osmolality of collected fluid were measured. Neither chemical Cl concentration nor osmolality of the collected fluid decreased significantly below their respective perfusion fluid values in tubules from non-DOCA-treated rabbits, but there was a significant decrease in the chemical Cl concentration (10-42 meq/l) and osmolality (10-42 mosmol/kg H2O) of collected fluid in tubules from DOCA-treated rabbits. In group 3, unidirectional Cl permeabilities from lumen-to-bath were determined during the passage of current down the perfusion pipette. Alterations of the average lumen potential, -35 .+-. 4 and +28 .+-. 2 mV, did not influence unidirectional Cl movement suggesting that the cortical collecting tubule is quite impermeable to Cl. In group 4, unidirectional Cl permeability from lumen-to-bath was measured before and after substitution of NaCH3SO4 for NaCl in the bath. Replacement of Cl by CH3SO4 reversibly decreased apparent Cl permeability from 2.41 .+-. 0.50 to 0.69 .+-. 0.08 .times. (10-5 cm/s) demonstrating that 36Cl permeability is dependent on the chemical concentration of Cl. The cortical collecting tubule was able to reabsorb salt under the modulation of circulating mineralocorticoids and, thus, may participate in overall volume homeostasis. The Cl permeability and major portion of isotopic Cl flux across the cortical collecting tubule was via exchange diffusion. Under certain circumstances the cortical collecting tubule may act as a diluting segment.