inducible NO production and secondary cardiovascular tissues injury. Therefore, we determine the intrinsic MA concentrations and their effects on inducible NOS function and excitotoxic injury. Kinetic studies demonstrated that the K(m) for l-arginine is 5.58 µM with a V(max) of 0.67 µM/ng.min, while K(i) values of 3.3 µM and 2.8 µM were determined for ADMA and NMA, respectively. Normal inducible concentrations of all NOS-inhibiting MA were determined to be approximately 2-3.5 µM, while l-arginine concentration is more than 100 µM. These MA levels result no significant inhibition of NO generation from iNOS in normal tissues. However, during the diseases or injury such as atherosclerosis and wound healing , L-arginine concentration can decrease to 10 µM or lower; while MA concentration can increase to above 10 µM and thus can result in >50% inhibition of NO generation from iNOS. Thus modulation of these MA levels would dramatically inhibit NO generation from iNOS and suppress NO-mediated cardiovascular injury. Pharmacological modulation of the levels of these intrinsic NOS inhibitors offers a novel approach to modulate iNOS function and injury. doi: 309 Gold Nanoparticles­mediated Releasing of Nitric Oxide from RSNOs Hongying Jia1, Yang Liu1, Xu Han1, Qiu Tian1, and Libo Du1 1Institute of Chemistry Chinese Academy of Science, Beijing The diatomic free radical nitric oxide (•NO) plays an important role in multiple processes such as vasodilation, angiogenesis, neurotransmission, and the immune response. This specific biological activity of NO indicates chemical systems capable of generating NO may prove useful for therapeutic applications. As such, small-molecule NO donor complexs have been developed to chemically store and release NO. S-nitrosothiols (RSNOs) belong to an important group of NO donors. Therefore, it is very significante for clinic function (e.g. inhibit platelet adhesion and smooth-muscle tone) to release or generate controllable concentration of NO from RSNOs. Our previous studies [1] have found that the gold nanoparticles can induce NO releasing by reacting with endogenous RSNOs in serum. Herein, NO concentration mediated-generation system is developed by gold nanoparticles catalytic decomposition of endogenous RSNOs. The modulate effect of gold nanoparticles on NO donor decoposition is realized by changing the size or protected group of gold nanoparticles. It is anticipated that gold nanoparticles have some therapeutic function by controlling NO release from endogenous RSNOs, owing to NO’s ability to inhibit platelet adhesion and activation. References: [1] Jia HY, Zhang XJ, Liu Y, et. al. J. Am. Chem. Soc. 131 (2009) 40–1. doi: 310 Hydrogen Sulfide and Nitric Oxide Cross­talk: Evidence for Hydrogen Sulfide Mediated Nitric Oxide Production from Nitrite Maria Letizia Lo Faro1, Torsten Burkholz1, Matthew Whiteman1, and Paul G. Winyard1 1Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom Nitrite (NO2

–) has been suggested to be an alternative source of nitric oxide (•NO) in vivo. Physiological mechanisms suggested for NO2

– reduction to •NO have included: the mitochondrial electron transport system, xanthine oxidase, deoxyhemoglobin and simply the protonation of NO2

–.

This current work investigated the effects of hydrogen sulfide (H2S), a recently identified gaseous mediator, on the release of •NO from NO2

– using electron paramagnetic resonance spectroscopy (EPR) spin trapping, chemiluminescence, amperometry and cGMP accumulation in cultured human T-lymphocytes and murine RAW264.7 macrophages as an index of •NO bioavailability. The spin trap used was the Fe2+ complex of N-methyl-D-glucamine dithiocarbamate (MGD). H2S was generated using the sulfide salts Na2S and NaSH and the novel slow releasing H2S donors GYY4137, MC0510 and MC0610. In the presence of NO2

– and the spin trap and also following incubation with H2S donors, a triplet EPR signal attributable to the NO-Fe2+-(MGD)2 spin adduct was detected. Peak integration of the EPR spectra of spin-trapped •NO showed that 5 minutes incubation (at room temperature) of 1mM NO2

– with 1mM NaSH

increased •NO formation compared to NO2– alone, with increases

of 48±11% (1 SD) and 51±10% at pH 4 and pH 7.4, respectively (n=4). Chemiluminescence and amperometry independently confirmed that sulfide reduced NO2

– directly to •NO, at pH 7.4, suggesting a possible alternative pathway for NO2

– reduction and •NO formation, via H2S in physiological systems. Hydrogen sulfide-induced release of •NO from NO2

– provides further evidence of a cross talk between •NO and H2S, gases which share similar physiological properties. It also opens up the possibility of using H2S pharmacologically to modulate •NO release from the “alternative” NO2

– storage pool. doi: 311 Effects of Chronic Renal Failure on L­arginine­Nitric Oxide Pathway and Arginase in Erythrocytes Monique B. Moss1, Mariana A.S. Siqueira1, Marcela A. Martins1, Natália R. Pereira1, Sérgio F.F. Santos1, Antônio Cláudio Mendes Ribeiro1, and Tatiana M.C. Brunini1 1Universidade do Estado do Rio de Janeiro Chronic renal failure (CRF) is characterized by the presence of endothelial dysfunction in parallel with diminished nitric oxide (NO) bioavailability. L-arginine is a cationic amino acid that is converted into NO, by a family of enzymes referred as NO synthase (NOS). This amino acid is also converted into L-ornithine and urea by arginase and both enzymes compete for the same substrate. Recent evidences have shown that red blood cells (RBC) produce and release NO, regulating RBC deformability and promoting vasodilatation. The aim of the present study was to investigate the effects of CRF on L-arginine-NO pathway, arginase pathway and RBC osmotic fragility (OF). In this study were included 13 CRF patients under HD and 12 controls. L-arginine influx was determined by measuring the uptake of L-[3H]–arginine (5-100 µM). N-ethylmaleimide was used to isolate transport system y+L. Basal NOS activity was measured by the conversion of L-[3H]-arginine into L-[3H]-citrulline. Arginase I and II expressions were accessed by Western Blotting. Arginase activity was analyzed in RBC lysate through the conversion of [C14]-L-arginine into [C14]-urea. OF was assessed by the incubation of RBC with different concentrations of NaCl. Students t-test was used for statistical analysis and values were considered significantly different when p<0.05. L-arginine influx was increased in RBC from CRF patients, however, it was not detected any difference on NOS activity. RBC express only arginase I and CRF patients over express arginase I associated with increased enzyme activity. RBC from CRF patients showed increased OF at 0.7 and 0.65 % NaCl. In summary, RBC from CRF patients under HD show higher osmotic fragility associated with increased L-arginine influx that is possibly shifted towards arginase pathway. Financial Support: FAPERJ, CNPq, CAPES.  doi:

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