Potassium (K) is an essential electrolyte for cellular functions in living organisms, and disturbances in K+ homeostasis could lead to various chronic diseases (e.g. hypertension, cardiac disease, diabetes, and bone health). However, little is known about the natural distribution of stable K isotopes in mammals and their application to investigate bodily homeostasis and/or as biomarkers for diseases. Here, we measured K isotopic compositions (δ41K, per mil deviation of 41K/39K from the NIST SRM 3141a standard) of brain, liver, kidney, and red blood cells (RBCs) from 10 mice (five females and five males) with three different genetic backgrounds. Our results reveal that different organs and RBCs have distinct K isotopic signatures. Specifically, the RBCs have heavy K isotopes enrichment with δ41K ranging from 0.67 to 0.08‰, while the brains show lighter K isotopic compositions with δ41K ranging from -1.13 to -0.09‰ compared to the livers (δ41K = -0.12 ± 0.58‰) and kidneys (δ41K = -0.24 ± 0.57‰). We found that the K isotopic and concentration variability is mostly controlled by the organs, with a minor effect of the genetic background and sex. Our study suggests that the K isotopic composition could be used as a biomarker for changes in K+ homeostasis and related diseases such as hypertension, cardiovascular, and neurodegenerative diseases.

中文翻译：

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小鼠器官和红细胞中稳定的钾同位素分布：对生物标志物开发的影响。

钾 (K) 是生物体细胞功能必需的电解质，K+ 稳态紊乱可能导致各种慢性疾病（例如高血压、心脏病、糖尿病和骨骼健康）。然而，人们对稳定钾同位素在哺乳动物中的自然分布及其在研究身体稳态和/或作为疾病生物标志物中的应用知之甚少。在这里，我们测量了 10 只小鼠（5 只雌性和 5 只雄性）的脑、肝、肾和红细胞 (RBC) 的 K 同位素组成（δ41K，与 NIST SRM 3141a 标准的 41K/39K 的每密耳偏差），不同的遗传背景。我们的结果表明，不同的器官和红细胞具有不同的 K 同位素特征。具体而言，红细胞具有重 K 同位素富集，δ41K 范围为 0.67 至 0.08‰，与肝脏 (δ41K = -0.12 ± 0.58‰) 和肾脏 (δ41K = -0.24 ± 0.57‰) 相比，大脑显示出较轻的 K 同位素组成，δ41K 范围为 -1.13 至 -0.09‰。我们发现钾同位素和浓度变异主要由器官控制，遗传背景和性别的影响较小。我们的研究表明，K 同位素组成可用作 K+ 稳态变化和相关疾病（如高血压、心血管和神经退行性疾病）变化的生物标志物。