Aging of membrane transport mechanisms in the central nervous system. GABA transport in rat cortical synaptosomes.

A kinetic study of sodium dependent GABA transport has been made in synaptosomes from 30-month old Long-Evans rats and compared to results from 2-month old animals. Initial velocity of uptake was measured as a function of both sodium and GABA concentration, and these data were than fitted to the model which was found to give best fit for the 2-month data. An excellent fit was also obtained for the 30-month data. Thus there has been no change with age in the fundamental mechanism by which carrier, sodium, and GABA interact in the process of transport. However, quantitative changes were found to occur with age both in initial velocity of uptake and in those constants which quantitate the model. The rate equation for the model was utilized along with the best fit constants to define and calculate certain parameters which were then used to quantitatively compare the transport mechanism in young and aged animals.