Griess method for nitrite measurement of aqueous and protein-containing samples.
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Chromatography, High Pressure Liquid↗
Biomedical subjects
Tienush Rassaf
Publications and source records attributed to Tienush Rassaf.
Concomitant S-, N-, and heme-nitros(yl)ation in biological tissues and fluids: implications for the fate of NO in vivo.
There is growing evidence for the involvement of nitric oxide (NO) -mediated nitrosation in cell signaling and pathology. Although S-nitrosothiols (RSNOs) have been frequently implicated in these processes, it is unclear whether NO forms nitrosyl adducts with moieties other than thiols. A major obstacle in assessing the significance of formation of nitrosated species is the limited reliability of available analytical techniques for measurements in complex biological matrices. Here we report on the presence of nitrosated compounds in plasma and erythrocytes of rats, mice, guinea pigs, and monkeys under basal conditions, in immunologically challenged murine macrophages in vitro and laboratory animals in vivo. Besides RSNOs, all biological samples also contained mercury-stable nitroso species, indicating the additional involvement of amine and heme nitros(yl)ation reactions. Significant differences in the amounts and ratios of RSNOs over N- and heme-nitros(yl)ated compounds were found between species and organs. These observations were made possible by the development of a novel gas-phase chemiluminescence-based technique that allows detection of nitroso species in tissues and biological fluids without prior extraction or deproteinization. The method can quantify as little as 100 fmol bound NO and has been validated extensively for use in different biological matrices. Discrimination between nitrite, RSNOs, and N-nitroso or nitrosylheme compounds is accomplished by use of group-specific reagents. Our findings suggest that NO generation in vivo leads to concomitant formation of RSNOs, nitrosamines, and nitrosylhemes with considerable variation between rodents and primates, highlighting the difficulty in comparing data between different animal models and extrapolating results from experimental animals to human physiology.
Animals↗
Evidence for in vivo transport of bioactive nitric oxide in human plasma.
Although hitherto considered as a strictly locally acting vasodilator, results from recent clinical studies with inhaled nitric oxide (NO) indicate that NO can exert effects beyond the pulmonary circulation. We therefore sought to investigate potential remote vascular effects of intra-arterially applied aqueous NO solution and to identify the mechanisms involved. On bolus application of NO into the brachial artery of 32 healthy volunteers, both diameter of the downstream radial artery and forearm blood flow increased in a dose-dependent manner. Maximum dilator responses were comparable to those after stimulation of endogenous NO formation with acetylcholine and bradykinin. Response kinetics and pattern of NO decomposition suggested that despite the presence of hemoglobin-containing erythrocytes, a significant portion of NO was transported in its unbound form. Infusion of NO (36 micromol/min) into the brachial artery increased levels of plasma nitroso species, nitrite, and nitrate in the draining antecubital vein (by < 2-fold, 30-fold, and 4-fold, respectively), indicative of oxidative and nitrosative chemistry. Infused N-oxides were inactive as vasodilators whereas S-nitrosoglutathione dilated conduit and resistance arteries. Our results suggest that NO can be transported in bioactive form for significant distances along the vascular bed. Both free NO and plasma nitroso species contribute to the dilation of the downstream vasculature.
Arteries↗
The L-arginine nitric oxide pathway: avenue for a multiple-level approach to assess vascular function.
Endothelial dysfunction is an early stage of atherosclerosis and has been attributed to impaired nitric oxide (NO) bioactivity and enhanced formation of oxygen-derived free radicals. Given that endothelial dysfunction is at least in part reversible, the assessment of altered NO availability is of important diagnostic and prognostic significance. Identification of such alterations may help to target asymptomatic individuals who are at risk for cardiovascular diseases and would likely benefit from preventive measures. Focusing on a single signaling pathway, we present here a multi-level approach for the early diagnosis of cardiovascular diseases by assessing molecular, biochemical, structural, and functional changes in the vascular wall.
Animals↗