POSTNATAL-DEVELOPMENT OF ATPASE ADPASE ACTIVITIES IN SYNAPTOSOMAL FRACTION FROM CEREBRAL-CORTEX OF RATS

ATPase-ADPase activities in synaptosomes from cerebral cortex was meas ured in rats of various ages (0-,7-,10-,14- and 21- and 60-90-days). T he activities (nmol P(i)/min/mg) increased steadily from birth, reachi ng maximum values at 21 days of age. The increase was primarily due to increases in V(max); the K(m) values are the same from birth until ad ult age. The developmental profile was similar for ATPase-ADPase activ ities and acetylcholinesterase from the same fraction. Several specifi c ATPase inhibitors and Ap5A (P1P5-di(adenosine-5)-pentaphosphate) did not interfere with the hydrolysis of ATP and ADP at all ages studied, suggesting that classical ATPases and adenylate kinase were not invol ved in the degradation of both nucleotides by synaptosomal fraction in the assay conditions. Other phosphatases were also ruled out. It is c onceivable that ATPase-ADPase activities play an important role in neu rotransmitter metabolism.