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.
Department of Human Physiology, Pedagogical University, Novosibirsk, Russia.
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Aizman
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Grahnquist
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Celsi
D000042:Absorption; D000328:Adult; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D004064:Digestive System / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017136:Ion Transport / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*
D011188:Potassium