Abstract
Extract: During postnatal brain development in the rat there is a progressive decrease in the Na+/K+ ratio, which correlated with increasing activity of Na+-K+-activated ATPase. Undernutrition during intrauterine and early postnatal development (4–6 days) did not alter the Na+/K+ ratio, although there was a deficit in brain weight. However, undernutrition during the suckling period retarded the progressive fall in Na+/K+ ratio and rise in ATPase activity. The altered Na+/K+ ratio in these animals did not appear to be caused by change in brain carbohydrate metabolism.
Developing rats undernourished until 4–6 days resembled the intrauterine growth-retarded human baby as regards deficits in body weight, relative sparing of the brain compared with other organs, and depleted carbohydrate reserves.
The undernourished 4–6-day-old rat tolerated asphyxia as well as the well nourished rat of the same age. After asphyxia, the Na+/K+ ratio reverted to unity and there was an increase in brain water. Liver carbohydrate reserves did not appear to be a limiting factor that determined the point of death.
Speculation: The normal gradients of Na+ and K+ between the cell and its environment in developing rat brain may be altered by asphyxia or undernutrition as a result of a defect in the Na+ pump mechanism. Such a defect may be caused by asphyxia at a time in rat brain development equivalent to that of the human brain in the perinatal period, i.e., in the first stages of the brain growth spurt. Undernutrition, however, may retard development of the Na+ pump only when its time of application includes the period of most rapid brain growth and maturation.
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Adlard, B., De Souza, S. & Dobbing, J. Effects of Growth Retardation and Asphyxia on Brain Electrolytes and on Glycolysis in Developing Rats. Pediatr Res 7, 494–499 (1973). https://doi.org/10.1203/00006450-197305000-00002
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DOI: https://doi.org/10.1203/00006450-197305000-00002