Sansoè G, Silvano S, Rosina F, Smedile A, Rizzetto M
Gastroenterology Division, Gradenigo Hospital, 10153 Turin, Italy.
J Intern Med. 2005 Apr;257(4):358-66. doi: 10.1111/j.1365-2796.2005.01459.x.
In preascitic cirrhosis increased sodium retention occurs in kidney distal tubule in spite of normal aldosterone plasma levels. No clearance technique can dissect the respective contribution to sodium retention exerted by Henle's loop, distal convoluted tubule and collecting duct, so we evaluated proximal and distal tubular sodium handling in preascites during two manoeuvres that temporarily increase aldosterone secretion.
Ten patients with compensated cirrhosis and nine controls were studied in recumbency, during standing and after dopamine receptor blockade with metoclopramide through: 4 h renal clearances of sodium, potassium, lithium and creatinine; plasma levels of active renin and aldosterone.
Whilst comparable in recumbency, aldosterone levels significantly rose during standing and after metoclopramide in both groups. In patients, dopaminergic blockade caused a fall of distal sodium delivery (P < 0.01) but urinary sodium excretion was unchanged because the reabsorbed fraction of distal sodium delivery also fell (P < 0.03). Cirrhotic patients showed the same findings in the passage from recumbency to standing.
In preascitic cirrhosis, the distal tubular segments of the nephron are able to cope with decreases in tubular flow by reducing reabsorption at an aldosterone-independent site (possibly the loop of Henle).
在腹水前期肝硬化患者中，尽管醛固酮血浆水平正常，但肾脏远曲小管仍会出现钠潴留增加的情况。目前尚无清除技术能够剖析亨利氏袢、远曲小管和集合管对钠潴留的各自作用，因此我们评估了在两种可暂时增加醛固酮分泌的操作过程中，腹水前期近端和远端肾小管对钠的处理情况。
对10例代偿期肝硬化患者和9名对照者进行了研究，研究内容包括卧位、站立位以及用甲氧氯普胺进行多巴胺受体阻断后，通过以下指标进行观察：钠、钾、锂和肌酐的4小时肾脏清除率；活性肾素和醛固酮的血浆水平。
两组在卧位时醛固酮水平相当，但站立位及使用甲氧氯普胺后，醛固酮水平均显著升高。在患者中，多巴胺能阻断导致远端钠输送减少（P < 0.01），但尿钠排泄未变，因为远端钠输送的重吸收分数也下降了（P < 0.03）。肝硬化患者从卧位转为站立位时也出现了相同的结果。
在腹水前期肝硬化中，肾单位的远端肾小管段能够通过在不依赖醛固酮的部位（可能是亨利氏袢）减少重吸收来应对肾小管流量的减少。
