Subcellular distribution of soluble and membrane-bound Arg-beta-naphthylamide hydrolyzing activities in the developing and aged rat brain.

The subcellular distribution of soluble and membrane-bound Arg-beta-naphthylamide-hydrolyzing activities was studied in the left and right rat brain during development and aging. During development, the soluble activity was heterogeneous, whereas adult animals showed the highest activity in the synaptosomal fraction. However, except in fetuses, membrane-bound activity was greatest in the microsomal fraction. Except in microsomal and myelin fractions, soluble and membrane-bound activities showed a decrease in 1-wk-old rats compared with fetuses and a subsequent increase to adult levels in 1-mo-old rats. This profile differed in the microsomal fraction, which increased steadily throughout development. In the synaptosomal fraction, both activities were lower in 24-mo-old rats than in 5-mo-old animals. No differences between the hemispheres were observed in soluble or membrane-bound fractions at any age tested.