Department of Medical Research, Holstebro Regional Hospital, Laegaardvej 12, 7500 Holstebro, Denmark.
Scand J Clin Lab Invest. 2012 Feb;72(1):78-86. doi: 10.3109/00365513.2011.635216. Epub 2011 Dec 12.
Potassium is the main intracellular cation, which contributes to keeping the intracellular membrane potential slightly negative and elicits contraction of smooth, skeletal and cardiac muscle. A change in potassium intake modifies both cardiovascular and renal tubular function. The purpose of the trial was to investigate the effect of dietary potassium supplementation, 100 mmol daily in a randomized, placebo-controlled, crossover trial of healthy participants during two periods of 28 days duration. The participants (N = 21) received a diet that was standardized regarding energy requirement, and sodium and water intake.
24-hour ambulatory blood pressure (ABP) and applanation tonometry were used to assess blood pressure, pulse wave velocity (PWV), augmentation index (AIx) and central blood pressure (CBP). Immunoassays were used for measurements of plasma concentrations of vasoactive hormones: renin (PRC), angiotensin II (Ang II), aldosterone (Aldo), atrial natriuretic peptide (ANP), vasopressin (AVP), pro-brain natriuretic peptide (pro-BNP),endothelin (Endo), urinary excretions of aquaporin 2 (AQP2), cyclic AMP (cAMP), and the β-fraction of the epithelial sodium channel (ENaC(ß)).
AQP2 excretion increased during potassium supplementation, and free water clearance fell. The changes in urinary potassium excretion and urinary AQP2 excretion were significantly and positively correlated. Aldo increased. GFR, u-ENaC- β, PRC, Ang II, ANP, BNP, Endo, blood pressure and AI were not significantly changed by potassium supplementation, whereas PWV increased slightly.
Potassium supplementation changed renal tubular function and increased water absorption in the distal part of the nephron. In spite of an increase in aldosterone in plasma, blood pressure remained unchanged after potassium supplementation.
钾是细胞内主要的阳离子，有助于保持细胞内膜电位轻微负性，并引起平滑肌、骨骼肌和心肌收缩。钾摄入量的变化会改变心血管和肾小管功能。本试验的目的是研究饮食钾补充（在随机、安慰剂对照、交叉试验中，健康参与者每日补充 100mmol 钾，持续 28 天）对参与者的影响。参与者（N=21）接受了标准化的饮食，该饮食在能量需求、钠和水摄入方面是标准化的。
24 小时动态血压（ABP）和平面张力测定法用于评估血压、脉搏波速度（PWV）、增强指数（AIx）和中心血压（CBP）。免疫测定法用于测量血管活性激素的血浆浓度：肾素（PRC）、血管紧张素 II（Ang II）、醛固酮（Aldo）、心房利钠肽（ANP）、血管加压素（AVP）、脑利钠肽前体（pro-BNP）、内皮素（Endo）、水通道蛋白 2（AQP2）、环磷酸腺苷（cAMP）和上皮钠通道β亚基（ENaC(β)）的尿排泄。
钾补充期间 AQP2 排泄增加，自由水清除率下降。尿钾排泄和尿 AQP2 排泄的变化呈显著正相关。Aldo 增加。GFR、u-ENaC-β、PRC、Ang II、ANP、BNP、Endo、血压和 AI 均不受钾补充的显著影响，而 PWV 略有增加。
钾补充改变了肾小管功能，增加了远曲小管对水的吸收。尽管血浆中醛固酮增加，但钾补充后血压保持不变。
