Effect of arginine on basal and high potassium-induced efflux of [H-3]D-aspartate from rat striatal slices

There are conflicting reports in the literature regarding the effects of ni tric oxide as well as the involvement of the cyclic GMP pathway on the tran smitter release. To study the influence of the availability of the nitric o xide precursor arginine on the glutamate transmission process, rat striatal slices preloaded with the tritiated glutamate analogue D-aspartate were us ed. L-Arginine stimulated in a concentration-dependent way (0.01-10.0 mM) t he high potassium-induced efflux of [H-3]D-aspartate. The basal release was increased only by 10 mM L-arginine. Neither the basal nor the depolarizati on-induced efflux of [3H]D-aspartate was affected by D-arginine. The L-argi nine effect was abolished by the nitric oxide synthase inhibitor L-arginine methyl ester and was not modified by cyclic GMP. Only at high concentratio ns of L-arginine (10 mM) could an elevation of cyclic GMP level be demonstr ated. The results are discussed in terms of direct presynaptic action of nitric o xide on [H-3]D-aspartate efflux and a possible modulation of glutamate rele ase by the availability of arginine. (C) 1998 IBRO. Published by Elsevier S cience Ltd.