title: Nitric oxide synthase activity and L-arginine metabolism in the retinas from streptozotocin-induced diabetic rats.
abstract: 1. Nitric oxide synthase (NOS) activity was studied in the retinas from normal rats and in the retinas from two groups of streptozotocin-induced (8 days and 4 months) diabetic rats. In each animal group, the NOS activity was correlated to the concentration of amino acids related to L-arginine metabolism and to L-arginine uptake. 2. Retinas from both groups of streptozotocin-induced diabetes (8 days and 4 months) showed an increased NOS activity compared with the NOS activity in retinas from normal rats. In retinas lysate from normal rats, the NOS activity was most potently inhibited by NO-Arg (1 mM), whereas, in both groups of streptozotocin-induced diabetes, the NOS activity was most potently inhibited by the NOS inhibitor aminoguanidine (0.5 mM). 3. The basal levels of the amino acids related to L-arginine metabolism-namely, L-arginine, L-citrulline, L-ornithine and L-glutamine-in retinas from both groups of rats with streptozotocin-induced diabetes were decreased compared with the amino acid levels in retinas from normal rats. 4. The uptake of L-[3H]arginine in retinas from both groups of rats with streptozotocin-induced diabetes was increased compared with the uptake of of L-[3H]arginine in retinas from normal rats.
authors.affiliation: Center of Ophthalmology, Biomedical Institute for Research of Light and Image, Coimbra, Portugal. analia@imagem.ibili.uc.pt
authors.forename: A
authors.initials: A
authors.lastname: do Carmo
authors.forename: C
authors.initials: C
authors.lastname: Lopes
authors.forename: M
authors.initials: M
authors.lastname: Santos
authors.forename: R
authors.initials: R
authors.lastname: Proença
authors.forename: J
authors.initials: J
authors.lastname: Cunha-Vaz
authors.forename: A P
authors.initials: AP
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000378:metabolism*; D013311:Streptozocin
chemical_list: D013311:Streptozocin; D001120:Arginine; D019001:Nitric Oxide Synthase