TY - CHAP M1 - Book, Section TI - Disorders of Potassium Balance: Hypo- and Hyperkalemia A1 - Emmett, Michael A1 - Wiederkehr, Michael R. A2 - Lerma, Edgar V. A2 - Rosner, Mitchell H. A2 - Perazella, Mark A. PY - 2017 T2 - CURRENT Diagnosis & Treatment: Nephrology & Hypertension, 2e AB - Potassium is the principal cation of the intracellular fluid (ICF) where its concentration is between 120 and 150 mEq/L. The extracellular fluid (ECF) and plasma potassium concentration [K] is much lower—in the 3.5- to 5-mEq/L range. This very large transcellular gradient is maintained by active K transport via the Na/K ATPase pumps present in all cell membranes and the ionic permeability characteristics of these membranes. The resulting 30–40 fold transmembrane [K] gradient is the principal determinant of the transcellular resting potential gradient, which is about 90 mV, with the cell interior negative (Figure 4–1). Normal cell function requires maintenance of the ECF [K] within a relatively narrow range. This is particularly important for excitable cells such as myocytes, conducting tissues, and neurons. The pathophysiologic effects of hypokalemia and hyperkalemia on these cells result in most of the clinical manifestations. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1149111632 ER -