Inhibition of glutamate release by arachidonic acid in rat cerebrocortical synaptosomes.
The action of arachidonic acid on glutamate release in rat cerebrocortical synaptosomes was investigated. The Ca(2+)-dependent release of glutamate evoked by 4-aminopyridine (4-AP) was inhibited by arachidonic acid (0.5-10 microM), but the KCl-evoked release was not modified. The Ca(2+)-independent release of glutamate was insensitive to low concentrations of arachidonic acid, but higher concentrations of this free fatty acid (30 microM) induced a slow efflux of cytoplasmic glutamate. The decrease in the Ca(2+)-dependent release of glutamate by arachidonic acid was consistent with a reduction in both the depolarization and the subsequent rise in the cytoplasmic free Ca2+ concentration induced by 4-AP in the nerve terminal. The inhibitory action by arachidonic acid observed in glutamate release was reversed in the presence of the K(+)-channel blocker tetraethylammonium.
Herrero
I
I
Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
Miras-Portugal
M T
MT
Sánchez-Prieto
J
J
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D016257:Fura-2; D005971:Glutamates / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D001095:Arachidonic Acids; D005971:Glutamates; D013757:Tetraethylammonium Compounds; D016718:Arachidonic Acid; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D002118:Calcium; D016257:Fura-2