MODULATION OF GLUTAMINE SYNTHESIS IN CULTURED ASTROCYTES BY NITRIC-OXIDE

1. Previous results suggest that glutamine synthesis in brain could be modulated by nitrix oxide, The aim of this work was to assess this po ssibility. 2. As glutamine synthetase in brain is located mainly in as trocytes, we used primary cultures of astrocytes to assess the effects of increasing or decreasing nitrix oxide levels on glutamine synthesi s in intact astrocytes. 3. Nitric oxide levels were decreased by addin g nitroarginine, an inhibitor of nitric oxide synthase, To increase ni tric oxide we used S-nitroso-N-acetylpenicillamine, a nitric oxide gen erating agent, 4. It is shown that S-nitroso-N-acetylpenicillamine dec reases glutamine synthesis in intact astrocytes by approximate to 40-5 0%. Nitroarginine increases glutamine synthesis slightly in intact ast rocytes, 5. These results indicate that brain glutamine synthesis may be modulated in vivo by nitric oxide.