Changes in renal glutamate content during development.

The amount of glutamate per microgram protein was measured in renal mitochondria and homogenates as a function of age of rats. Glutamate was higher in the youngest (5-day-old) animals examined, it decreased gradually until about 30 days of age and reached mature levels in animals older than 40 days. The decrease in mitochondrial glutamate content was greater than the decrease in cortical homogenates. Chronic acidosis led to lower levels of glutamate in mature animals, particularly in mitochondria, but produced no effect in either mitochondria or homogenates obtained from kidneys of pups. These observations provide a basis for the hypothesis that high glutamate concentrations in the kidneys of neonatal animals can inhibit mitochondrial glutaminase and thereby limit ammoniagenesis in the postnatal period.