EFFECT OF NITRIC-OXIDE DONORS ON GABA UPTAKE BY RAT-BRAIN SYNAPTOSOMES

The effect of nitric oxide donors and L-arginine on the uptake of GABA was studied in synaptosomes purified from rat brain. The neurotransmi tter uptake was significantly reduced by S-nitrosoacetylpenicillamine and by sodium nitroprusside, although in this case to a lesser extent. A slight inhibitory effect was found preincubating rat brain synaptos omes with 1 mM L-arginine as well. The S-nitrosoacetylpenicillamine ef fect gradually disappeared with decomposition of the substance by expo sure to light. The nitric oxide effect appears to be mainly due to a d ecrease in the V for synaptosomal GABA uptake and seems to be related to a partial collapse of nerve endings ionic gradients. Functionally, it could result over time in a reduced availability of GABA at the syn apses involved.