Characterization of the hypotensive effect of S-nitroso-N-acetylcysteine in normotensive and hypertensive conscious rats.

S-Nitrosothiols (RSNOs) are potent vasodilators found naturally in vivo. A variety of synthetic RSNOs have been considered as potential nitric oxide (NO) donors for biomedical applications. We have characterized the hypotensive effect of the RSNO S-nitroso-N-acetylcysteine (SNAC) in normotensive and hypertensive conscious rats. SNAC reduced the medium arterial pressure in a dose-response manner in both normotensive and hypertensive animals. At the same doses (EC(50) of SNAC), SNAC showed a vasodilator effect in normotensive rats more potent and more prolonged than that of sodium nitroprusside (SNP). The hypotensive effect of SNAC was also more potent in methylene blue-treated rats, where the cGMP-dependent pathway had been blockaded. These data indicate that SNAC acts by both cGMP-dependent and cGMP-independent pathways. It was also shown that the thiol N-acetylcysteine (NAC) potentiates the action of SNP in hypertensive rats, pointing to the mediation of thiols in the vasodilator action of SNP in this condition. Such mediation may involve the formation of a more potent thiol complex with the nitroprusside anion or the transfer of NO to NAC, generating SNAC as a primary vasoactive species. The kinetic monitoring of the decomposition reactions of SNAC and SNP showed that both compounds are quite stable under the infusion conditions used. Therefore, their vasodilator action cannot be assigned to their breakdown with release of free NO in solution. As the two compounds are unlikely to cross the plasmalemma of smooth muscle cells, their actions are probably associated with the mediation of endogenous thiols in transnitrosation reactions.

Effect of flavonoids morin: quercetin and nicotinic acid on lipid metabolism of rats experimentally fed with triton

Aterosclerose é uma doença coronária onde a deposiçäo de lipídeos nas artérias leva a problemas na circulaçäo sanguínea. O presente trabalho avalia a açäo dos flavonóides morina, quercetina e ácido nicotínico isoladamente e em associaçäo no metabolismo lipídico em ratos hiperlipidêmicos. Foram analisados os níveis de colesterol, colesterol HDL e tricilfliceróis no soro sanguíneo após administraçäo via intraperitoneal, dos compostos flavononoídicos dissolvidos em propileno glicol na dose de 5mg/kg de peso corporal. Quercetina mostrou o maior percentual de reduçäo do colesterol. para colesterol HDL os melhores resultados foram obtidos com ácido nicotínico isoladamente, enquanto a associaçäo morina-ácido nicotínico mostrou os melhores resultados para triacilgliceróis. Os resultados mostraram que os flavonóides podem ser benéficos no tratamento de doença coronariana