Regulation of sodium metabolism and extracellular fluid volume during development

In addition to regulating developmental changes in body fluid content, the newborn kidney must maintain a positive sodium balance to ensure adequate body growth. Mechanisms by which the developing organism perceives changes in volume and the manner in which the kidney responds to these changes have been reviewed. Perception of changes in ECF volume is sensed by volume receptors that involve central nervous system signal processing (e.g., low- and high-pressure volume receptors) before influencing the kidney by way of the renal nerves or that are directly coupled with the kidney and do not involve central nervous system processing (e.g., juxtaglomerular apparatus, ANF, hepatic factors). Results presently available demonstrate that these mechanisms are functional early in life and that their sensitivity changes during development in accordance with the needs of the organism. In addition, the developing kidney has unique characteristics that allow it to maintain a positive sodium balance necessary for growth.