Physiology of renal sodium transport
Physiology of renal sodium transport
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DOI：
10.1097/00000441-200001000-00005
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发表时间：
2000-01-01
影响因子：
3.1
通讯作者：
Greger, R
中科院分区：
文献类型：
--
作者：
Greger, R
从简单的清除研究到离子转运体的分子鉴定，使用了一系列方法进行的大量研究增加了我们对大约1.7kgNaC l和180kgH2O是如何被人的肾小管吸收的，以及如何微调尿液排泄以满足体内平衡要求的理解。这篇综述将总结我们目前的理解。在近端肾单位，大约60%到70%的过滤的Na+和H2O与大约90%的过滤的HCO3-一起被吸收。确切的数量由许多调节因素决定，如肾小管平衡、血管紧张素II、内皮素、交感神经支配、甲状旁腺激素、多巴胺、酸碱状态等。吸收的基本成分是腔膜Na+/H+交换和基底外侧(Na++K+)-ATPase。在Henle环的粗大升支，有20%~30%的过滤后的氯化钠通过(Na++K+)-ATPase驱动的Na(+)2Cl(-)K(+)共转运被吸收。在这个肾单位没有水被吸收。转运速率由Na+负荷和几种激素和神经递质决定，包括前列腺素、甲状旁腺激素、胰高血糖素、降钙素、精氨酸加压素(AVP)和肾上腺素。在远端小管中，约5%~10%的过滤负荷通过(Na++K+)-ATPase驱动的管腔膜Na+-Cl-共转运而被吸收。转运的速度也是由输送的负荷以及几种激素和神经递质决定的。收集管的任务之一是控制大约10%到15%的过滤水的吸收，由AVP调节，以及只有几个百分比的过滤钠离子的吸收，由醛固酮和利钠激素控制。水的吸收通过水通道蛋白2穿过管腔膜，通过水通道蛋白3通道通过基侧膜，并由逆流浓缩系统建立的渗透梯度驱动。Na+的吸收是通过底侧(Na++K+)-ATPase驱动的腔膜上的Na+通道发生的。在没有药物干预的情况下，尿钠的排泄量可以在过滤负荷的0.1%到不超过3%之间变化，水的排泄量可以在0.3%到15%之间变化。
A wealth of studies performed with a spectrum of methods spanning simple clearance studies to the molecular identification of ion transporters has increased our understanding of how approximately 1.7 kg of NaCl and 180 L of H2O are absorbed by renal tubules in man and how the urinary excretion is fine-tuned to meet homeostatic requirements. This review will summarize our current understanding. In the proximal nephron, approximately 60 to 70% of the filtered Na+ and H2O is absorbed together with approximately 90% of the filtered HCO3-. The exact quantities are determined by many regulatory factors, such as glomerulotubular balance, angiotensin II, endothelin, sympathetic innervation, parathyroid hormone, dopamine, acid base status and others. The essential components of absorption are luminal membrane Na+/H+ exchange and the basolateral (Na+ + K+)-ATPase. In the thick ascending limb of the loop of Henle, 20 to 30% of the filtered NaCl is absorbed via Na(+)2Cl(-)K(+) cotransport driven by the basolateral (Na+ + K+)-ATPase. No H2O is absorbed at this nephron site. The transport rate is determined by the Na+ load and by several hormones and neurotransmitters, including prostaglandins, parathyroid hormone, glucagon, calcitonin, arginine vasopressin (AVP), and adrenaline. In the distal tubule, some 5 to 10% of the filtered load is absorbed via Na+Cl- cotransport in the luminal membrane driven by the basolateral (Na+ + K+)-ATPase. The rate of transport is again determined by the delivered load and by several hormones and neurotransmitters. One of the tasks of the collecting duct is to control the absorption of approximately 10 to 15% of the filtered H2O, regulated by AVP, and just a few percent of the filtered Na+, controlled by aldosterone and natriuretic hormone. The water absorption proceeds through the luminal membrane via aquaporin 2 and through the basolateral membrane via aquaporin 3 channels and is driven by the osmotic gradient built up by the counter current concentrating system. The Na+ absorption occurs via Na+ channels present in the luminal membrane driven by the basolateral (Na+ + K+)-ATPase. With no pharmacological interference, urinary excretion of Na+ can vary between less than 0.1% and no more than 3% of the filtered load, and that of H2O can vary between 0.3 and 15%.