Potassium homeostasis: ontogenic aspects

Potassium is the most abundant intracellular cation and plays an important role in a variety of cell functions. Potassium regulation and homeostasis during infancy are, owing to growth and development, different from in later life: infants need to retain more K + than adults, to avoid growth retardation. Since the K + requirements are different in infants and in adults, the mechanisms regulating K + homeostasis also need to be different. This paper includes a review of the literature concerning the regulation of internal and external K + balances during ontogeny. We examined the role of gastrointestinal tract, kidney and some tissue stores in K + excretion and distribution during development. We conclude that positive K + balance in infancy is characterized by higher K + absorption in gut, lower K + secretion/excretion in kidney and immaturity of the mechanisms regulating intra/extracellular K + distribution. Several factors contribute to maintain the positive K + balance. They include higher expression of absorptive transporters in colon and probably in kidney, lower expression of secretive transporters in colon and kidney, lower renal K + excretion following K + loading, immaturity of hepato‐renal K + reflex mechanism, immaturity of tissue K + binding/ releasing capacity and immaturity of the neuro‐hormonal control of K + transport in several organs.