Via nitrato-nitrito-óxido-nítrico: aspectos fisiológicos e terapêuticos / Nitrate-nitrite nitric oxide pathway: physiological and therapeutical aspects

A formação de NO nitrito-dependente é uma via que complementa a via enzimática, pois atuam em paralelo, porém, quando a suplementação de oxigênio está comprometida, há redução na expressão das enzimas NOS, comprometendo a formação de NO a partir desta via. Então, entra em ação a via nitrito-dependente, a qual desempenha funções favoráveis em condições de déficit de oxigênio. Assim sendo, esta é uma via de papel importantíssimo em condições patológicas que cursam com isquemia, tornando necessário garantir o armazenamento deste substrato, seja via farmacológica ou pela dieta alimentar. O papel na fisiologia, fisiopatologia, nutrição e terapêutica do nitrito e nitrato podem gerar frutos promissores para o desenvolvimento de novos caminhos na abordagem de algumas doenças e mudar a visão atual sobre os constituintes alimentares, no âmbito da saúde e doença. O presente texto tem como objetivo revisar e discutir as funções biológicas e o metabolismo do NO independente da via enzimática no organismo, além de abordar o uso terapêutico de nitrato ou nitrito em condições de doença.

The nitrite-dependent NO pathway is one that complements the enzymatic pathway of NO release, because they act in parallel, but when oxygen supplementation is compromised there is a reduction in the expression of NOS enzymes affecting the formation of NO from this pathway. Thus, the nitrite-dependent pathway swings into action, which plays favorableroles under oxygen deficit conditions. Therefore this is a very important role in pathological conditions that occurs with ischemia, making it necessary to ensure the storage of this substrate, either through a pharmacological or nutritional diet. The role in physiology, pathophysiology, nutrition and treatment of nitrite and nitrate can bear fruit for the development of promising new grounds in addressing some diseases and to change the current view on foods, health and diseases. The aim of this paper is to review and discuss the biological functions and metabolism of NO enzymatic-independent pathway in the body and to discuss the therapeutic use of nitrate or nitrite in disease conditions.

Nitrate levels and stages of growth in hypernodulating mutants pf Lupinus Albus. I. N2 fixation potential

This work aimed to evaluate physiological parameters, nodulation response and N2 fixation rate in mutants of Lupinus albus in comparison with the standard Multolupa cultivar. Two nitrate levels (0 and 5mM) and two evaluation periods (7 and 10 weeks) were used. Significant differences were observed among genotypes, in relation to fresh nodule weight, nitrate levels and growth stages. The overall average for nitrate level differed between them where 5mM severely inhibieted the number of nodules, reaching a 49.5 (per cent) reduction in relation to treatment without nitrate. There were no behaviour differences among genotypes, nor among evaluation periods. Although the level of nitrate did not influence the production of shoot dry matter in relation to the average among levels applied, the L-135 genotype, being an inefficient mutant, reached very low values. There were no significant differences in electron allocation coefficient (EAC) among nitrate levels, nor among genotypes studied. However , the evaluation periods revealed differences, where the EAC for the seventh week had a higher value than that for the tenth week, when a 5mM aplication was evaluated. The N2 fixation rate (N2FIX) showed the existence of the nitrate interference in fixation, given that the application of 5mM severely reduced. However, there were no differences among the genotypes and it was noted that the fixation rate was much higher in those that received nitrate. The L-88 and L-62 genotypes were the ones that have shown best adaptability in this experiment, thus being able to be recommended for new studies with higher nitrate levels and different evaluation periods. The nitrate (5mM) interferes in the nitrogen fixation rate, given that all the genotypes were affected by the level applied.

Efectos fisiopatologicos del oxido nitrico y su relacion con el estres oxidativo / Psysiopathologic effects of nitric oxide and its relationship with oxidative stress

El óxido nítrico (NO.) es producido por la oxidación de la arginina a citrulina, una reacción catalizada por las enzimas óxido nítrico sintasas (NOS). Se acepta que esa reacción es la única capaz de producir NO en los sistemas biológicos, en condiciones normales o patológicas. El NO regula diferentes funciones en células y tejidos de mamíferos, tales como: (a) el control de la presión sanguínea; (b) la relajación del tono del músculo liso arterial; (c) la agregación y adhesión plaquetaria; (d) la neurotransmisión; (e) la función neuro-endócrina. El NO. también participa en la destrucción de microorganismos patógenos y de células tumorales por leucocitos y macrófagos. La producción de anión superóxido (O2-) y NO. ha sido asociada al desarrollo de muchas patologías, pero recientemente se ha comprobado que la interacción de esas moléculas genera el ión peroxintrito (ONOO-), lo que constituye un importante mecanismo fisiopatológico pues, como oxidante, el ONOO- ataca un gran número de blancos biológicos. Por su influencia sobre la producción de ONOO-, el balance entre la producción de NO y O2- es crítico en la etiología de procesos como hipertensión, ateroesclerosis, enfermedades neurodegenerativas, infecciones virales, daño por isquemia-reperfusión y cáncer.

Effect of nitrate, phosphate and salinity on the growth of the unicellular algae nannochloropsis saline and isochrysis galbana

Experiments concerning the optimization of growth concentration of nutrient salts [nitrate and phosphate] and salinity of the marine microalgae Nannochloroposis salina and Isochrysis galbana are decreased. The maximum growth rate of the former species obtained at nitrogen concentration of 9 g NO3-N L-1 and phosphorus of 0.81 mg PO4-P L-1 after 12 days incubation, which equivalent to 6 and 3 folds, respectively, of them needed for the second species to reach its maximum [1.5 mg NO3-N L-1 and 0.27 mg PO4-P L-1 at 12 and 14 days, respectively]. The highest growth of these two species was recorded at salinity ranging from 25% to 30% on sea water medium enriched with the highest concentrations of nitrite and phosphate after 12 days of cultivation [average 17 and 12 x 106 cell ml-1 of the two species, respectively]. N. Salina contained 30.62% crude protein and 19.63% ether extract, while I. galbana contained half amount of both crude protein and ether extract [15.67% and 9.12%, respectively]. Consequently, N. salina needed more nitrogen ion than the second species in their growth, due to its high content of protein. In comparison with other algae, these two species contained high content of crude protein and fat and can easily massed production as good food item for aquaculture marine organisms