Alpha-latrotoxin releases both vesicular and cytoplasmic glutamate from isolated nerve terminals.
alpha-Latrotoxin causes a massive release of endogenous glutamate from guinea-pig cerebrocortical synaptosomes. There appear to be two components to the release. In the first 2 min following addition of 1.3 nM alpha-latrotoxin, glutamate release is largely energy dependent. Superimposed upon this release is a more slowly developing but ultimately much more extensive release of cytoplasmic glutamate together with gamma-aminobutyric acid and nonvesicular amino acids such as aspartate and alpha-aminoisobutyrate. In parallel with this cytoplasmic release there is an extensive depletion of ATP, a massive rise in cytoplasmic free Ca2+ concentration, and a severe restriction of synaptosomal respiratory capacity. The cytoplasmic release is only partially Na+ dependent, eliminating a simple reversal of the plasma membrane acidic amino acid carrier. It is concluded that alpha-latrotoxin releases both transmitter and cytoplasmic pools of amino acids in synaptosomes and causes a major disruption of terminal integrity.
McMahon
H T
HT
Department of Biochemistry, University of Dundee, Scotland.
Rosenthal
L
L
Meldolesi
J
J
Nicholls
D G
DG
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D004734:Energy Metabolism; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009411:Nerve Endings / Q000378:metabolism*; D012119:Respiration / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D013111:Spider Venoms / Q000494:pharmacology*
D000596:Amino Acids; D005971:Glutamates; D013111:Spider Venoms; D018698:Glutamic Acid; C020763:alpha-latrotoxin; D012964:Sodium; D002118:Calcium