Higashihara E, Kokko J P
Am J Physiol. 1985 Feb;248(2 Pt 2):F219-27. doi: 10.1152/ajprenal.1985.248.2.F219.
Recent studies have suggested that potassium, like urea, undergoes medullary recycling. The present cortical and papillary micropuncture studies were designed to confirm the existence of medullary potassium recycling and to determine whether acute infusions of aldosterone affected this phenomenon. Thus, nephron segmental analysis of potassium and sodium transport was conducted in adrenalectomized Munich-Wistar rats and similarly prepared rats that received aldosterone acutely to achieve physiological blood levels. The clearance results demonstrated that aldosterone has an acute antinatriuretic and a kaliuretic effect, whereas the micropuncture studies demonstrated that 1) aldosterone increases potassium secretion between early and late distal tubule punctures; 2) aldosterone causes an increase in delivery of potassium to the papillary collecting duct; 3) aldosterone does not increase potassium secretion across the papillary collecting duct; and 4) aldosterone significantly increases medullary potassium recycling as evidenced by increased quantities of potassium present at the bend of the loop of Henle in response to aldosterone infusions. Thus, the studies confirm the existence of potassium recycling and suggest that this phenomenon is a feedback system that, in part, regulates urinary potassium excretion.
近期研究表明，钾与尿素一样，会在髓质进行再循环。目前的皮质和乳头微穿刺研究旨在证实髓质钾再循环的存在，并确定急性输注醛固酮是否会影响这一现象。因此，对肾上腺切除的慕尼黑 - 维斯塔尔大鼠以及接受急性醛固酮输注以达到生理血药浓度的类似制备大鼠进行了肾单位节段性钾和钠转运分析。清除率结果表明，醛固酮具有急性利钠作用和排钾作用，而微穿刺研究表明：1）醛固酮增加早期和晚期远端小管穿刺之间的钾分泌；2）醛固酮导致输送到乳头集合管的钾增加；3）醛固酮不会增加穿过乳头集合管的钾分泌；4）醛固酮显著增加髓质钾再循环，这可通过输注醛固酮后亨利袢弯曲处钾含量增加得到证明。因此，这些研究证实了钾再循环的存在，并表明这一现象是一种反馈系统，部分调节尿钾排泄。
