Graduate School of Public Health, University of Puerto Rico, San Juan, Puerto Rico.
Am J Clin Nutr. 2010 Mar;91(3):597-603. doi: 10.3945/ajcn.2009.28400. Epub 2009 Dec 9.
Racial differences in the renal disposition of potassium may be related to mechanisms for the greater susceptibility to hypertension in blacks than in whites.
Our objective was to study the racial differences in the renin-angiotensin-aldosterone system and in potassium balance in black and white girls consuming a controlled diet that was low in potassium with 2 amounts of sodium intake (low compared with high).
The studies reported here were performed in 40 black and 28 white girls, aged 11-15 y, under highly controlled metabolic conditions. The studies comprised 2 sessions of 20-d metabolic balance sessions, at 2 amounts of dietary sodium intake (58 and 170 mmol . L(-1) . d(-1)), in a crossover design and with a constant dietary potassium intake of 50 mmol . L(-1) . d(-1). Repeated-measures analysis of variance was used to test for racial differences in potassium output and retention by sodium intakes.
Thirty black and 20 white girls completed the study. Urinary potassium excretion was lower in blacks than in whites, regardless of sodium intake (P < 0.05), with no differences in fecal or sweat potassium excretion. Cumulative potassium retention was significantly higher in blacks while consuming the low sodium diet. Plasma aldosterone concentrations after upright posture were significantly lower in blacks than in whites but were similar when supine, as were urinary aldosterone excretion rates. On week 3, blood pressure, body weight, urinary volume, creatinine, and serum sodium and potassium were similar.
The well-known racial difference in urinary potassium excretion appears to be at least in part due to greater renal retention of potassium in black girls.
钾在肾脏中的分布存在种族差异，这可能与黑人比白人更容易患高血压的机制有关。
我们的目的是研究在摄入低钾饮食且钠摄入量（低与高相比）不同的情况下，黑人和白人女孩的肾素-血管紧张素-醛固酮系统和钾平衡方面的种族差异。
本研究报告中的研究在 40 名黑人和 28 名白人女孩中进行，年龄为 11-15 岁，处于高度控制的代谢状态。这些研究包括 2 个为期 20 天的代谢平衡期，在 2 种不同的饮食钠摄入量（58 和 170mmol·L-1·d-1）下进行，采用交叉设计，钾的饮食摄入量保持在 50mmol·L-1·d-1。采用重复测量方差分析来检验钠摄入量对钾排泄和保留的种族差异。
30 名黑人和 20 名白人女孩完成了这项研究。无论钠摄入量如何，黑人的尿钾排泄量均低于白人（P<0.05），粪便或汗液中的钾排泄量没有差异。在摄入低钠饮食时，黑人的累积钾保留量明显更高。直立后血浆醛固酮浓度黑人明显低于白人，但仰卧时相似，尿醛固酮排泄率也相似。在第 3 周时，血压、体重、尿量、肌酐以及血清钠和钾均相似。
众所周知的尿钾排泄的种族差异至少部分归因于黑人女孩肾脏对钾的保留能力更强。
