连接小管：兔远端肾单位各节段的一个功能亚单位。

The connecting tubule: a functional subdivision of the rabbit distal nephron segments.

作者信息

Imai M

出版信息

Kidney Int. 1979 Apr;15(4):346-56. doi: 10.1038/ki.1979.46.

DOI:10.1038/ki.1979.46

Abstract

Studies on adenylate cyclase response of the nephron fragments to hormones and drugs have suggested that there is a functionally distinct segment tentatively called the connecting tubule (CNT), which is located between the distal (DT) and the cortical collecting tubule (CCT). The functional significance of these biochemical findings was examined with isolated rabbit renal tubules perfused in vitro. The transepithelial voltage (PDt) of the DT, CNT, and CCT were, respectively, -28.7 +/- 3.24 mV (24), -27.0 +/- 2.69 mV (24), and -3.5 +/- 2.14 mV (11) in the normal rabbits. The PDt of the CCT increased to -32.2 +/- 2.02 mV (33) when rabbits were pretreated for at least 3 days with deoxycorticosterone acetate, DOCA (1 mg/kg/day, i.m.), whereas the PDt of the DT and the CNT remained unchanged. The PDt of the CCT obtained from deoxycorticosterone acetate- (DOCA) treated animals decreased after addition of antidiuretic hormone (ADH) or isoproterenol (ISO) to the bath. The PDt of the CNT also responded to these agents, but the dose required to obtain the same response was quite different: The CNT was 100-fold more sensitive to ISO as compared to the CCT, whereas the CCT was 10-fold more sensitive to ADH than was the CNT. In contrast, the PDt of the DT did not respond to any of these agents, even at a higher concentration. After addition of ADH (200 microU/ml) to the bath, the osmotic water permeability (10(-8) cm2 . sec-1 . atm-1) of the CCT increased from 1.13 +/- 0.83 to 7.46 +/- 2.36, but that of the CNT remained low (0.36 +/- 0.78 in control vs. 0.48 + 0.64 after ADH). These observations support the view that the CNT is functionally distinct from either the DT or the CCT.

摘要

对肾单位片段对激素和药物的腺苷酸环化酶反应的研究表明，存在一个功能上不同的节段，暂称为连接小管（CNT），它位于远曲小管（DT）和皮质集合小管（CCT）之间。利用体外灌注的离体兔肾小管研究了这些生化发现的功能意义。正常兔中，DT、CNT和CCT的跨上皮电压（PDt）分别为-28.7±3.24 mV（24个样本）、-27.0±2.69 mV（24个样本）和-3.5±2.14 mV（11个样本）。当兔用醋酸脱氧皮质酮（DOCA，1 mg/kg/天，肌肉注射）预处理至少3天时，CCT的PDt增加到-32.2±2.02 mV（33个样本），而DT和CNT的PDt保持不变。从醋酸脱氧皮质酮（DOCA）处理的动物获得的CCT的PDt在向浴槽中加入抗利尿激素（ADH）或异丙肾上腺素（ISO）后降低。CNT的PDt也对这些药物有反应，但获得相同反应所需的剂量有很大差异：与CCT相比，CNT对ISO的敏感性高100倍，而CCT对ADH的敏感性比CNT高10倍。相反，即使在更高浓度下，DT的PDt对这些药物均无反应。向浴槽中加入ADH（200 μU/ml）后，CCT的渗透水通透性（10⁻⁸ cm²·秒⁻¹·大气压⁻¹）从1.13±0.83增加到7.46±2.36，但CNT的渗透水通透性仍然较低（对照时为0.36±0.78，ADH处理后为0.48 + 0.64）。这些观察结果支持了CNT在功能上不同于DT或CCT的观点。