Aging of the high affinity GABA transporter in synaptosomes from the hypothalamus of the rat.
Initial velocity of GABA uptake in hypothalamic synaptosomes has been measured in aged animals as a function of both sodium and GABA concentration and compared to previous studies in young animals. The data give good fit to the model found previously to give minimal best fit to control data. Thus it appears that aging has not resulted in a change in fundamental mechanism by which carrier, sodium, and GABA interact in the process of transport. However, changes were found in the constants which quantitate the model. As a consequence, there is a reduction in transport capability in the aged animals which is particularly apparent at the higher sodium concentrations. The best fit constants were used along with the rate equation from the model to calculate several kinetic parameters which are useful in comparing transport mechanisms. In the physiological range of sodium concentration, those kinetic parameters related to maximal transport capabilities declined with age, while apparent carrier affinities increased with age. Similar results were found in previous studies of GABA (Wheeler, 1982) and glutamic acid (Wheeler, 1980a) transport in cortical synaptosomes.
D000375:Aging; D000818:Animals; D007031:Hypothalamus / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009115:Muridae; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011963:Receptors, GABA-A; D012964:Sodium / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D012964:Sodium