Abstract
A simple procedure for isolating a fraction enriched in synaptic plasma membrane (SPM) vesicles from sheep brain cortex is described and is used in studying uptake and release of [3H]GABA. The crude synaptosomal fraction was subjected to osmotic shock and the lysate was subfractioned in a discontinuous density gradient of dextran T110. The activities of the enzyme markers of SPM, the phospholipid analysis and electron microscopy examination suggest that this fraction of SPM is of a purity similar to that of preparations previously described by more time consuming methods. Superfusion of SPM vesicles with sucrose, γ-aminobutyric acid (GABA), veratridine, increased [K+]o, or reduced [Cl−]o, induced the release of 4-amino-n-[2,3,3H]butyric acid ([3H]GABA) previously loaded into these vesicles by a Na+, Cl− and K+ dependent mechanism. Spontaneous and depolarization induced release of [3H]GABA does not require external Na+ or Cl−, whereas the release elicited by unlabeled GABA (homoexchange) is stimulated by Na+ or Cl−. Thus, both the uptake and homoexchange of [3H]GABA are influenced by Na+ and Cl−.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
