Abstract
Potassium (K+) is the predominant intracellular cation in the body. The intracellular [K+] is 140–150 mEq/L; in blood it is 3.5–5 mEq/L. Serum contains a slightly higher concentration of K+ than plasma because K+ is released from red blood cells during clot formation. Maintenance of a high cellular concentration of K+ is necessary for several cellular functions, including growth, nucleic acid and protein synthesis, and regulation of cell volume, as well as pH and enzyme activation. In addition, a high intracellular concentration of K+ is essential to the maintenance of the resting membrane potential for cellular excitability and contraction. The high intracellular K+ concentration is maintained by the Na/K-ATPase located in the cell membranes of all animal cells. The activity of this enzyme is influenced by a variety of hormones. The kidney is the primary route for K+ excretion. In general, K+ excretion in the urine, called kaliuresis, parallels dietary intake. The other route for K+ excretion is the colon. Under conditions of decreased renal function, K+ excretion by the colon is enhanced.
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Suggested Reading
Mount DB. Tubular potassium transport. In: Coffman TM, Falk RJ, Molitoris BA et al Editors. Schrier’s diseases of the kidney. Philadelphia: Lippincott Williams Wilkins; 2013, pp. 194–213.
Segal A. Potassium and the dyskalemias. In: Mount DB, Sayegh MH, Singh AJ, Editors. Core concepts in the disorders of fluid, electrolytes and acid-base balance. New York: Springer; 2013, pp. 49–102.
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Reddi, A. (2014). Disorders of Potassium: Physiology. In: Fluid, Electrolyte and Acid-Base Disorders. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-9083-8_14
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DOI: https://doi.org/10.1007/978-1-4614-9083-8_14
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