ATPase activity in glial cells and in neuromal perikarya of rat cerebral cortex during early postnatal development.

ATPASE activities during development have been studied in rat brain (SAMSON and QuI", 1967), in nerve-ending particle fractions from rat brain (ABDEL-LATIF, BRODY and RAMAHI, 1967) and in the cerebral cortex of the kitten (HUTTENLOCHER and RAWSON, 1968), as well as in preparations of synaptosomes and microsomes of rat brain (ABDEL-LATIF, SMITH and ELLINGTON, 1970). In a previous study, we compared the activities of Na-K ATPase and total ATPase of the cerebral cortical neuronal perikaryal fraction and glial cell fraction obtained as two separate populations by a bulk-isolation procedure (MEDZIHRADSKY, NANDHASRI, DOYAGA-VARGAS and SELLINGER, 1971). In that study on 18-20-day-old rats, the glial cell fraction exhibited levels of both activities markedly higher than those of the neuronal fraction. In the present work, the activity of the Na-K ATPase and of the ouabaininsensitive ATPase were determined in the two cellular fractions during the postnatal development of rat cerebral cortex. The results of this study may contribute to our knowledge of the formation of cellular processes and synaptic junctions, elements rich in Na-K ATPase (KUROKAWA, SAKAMOTO and &TO, 1965; SKOU, 1965; WHITTAKER, 1965; ABDEL-LATIF et a/., 1967; APPEL, AUTILIO, FESTOFF and ESCUETA, 1969), especially since HU~TENL~CHER and RAWSON (1968) found a close correlation between the activity of this enzyme and the spontaneous cortical activity during development in kitten cerebral cortex.