Effect of nitroxyl and nitric oxide on the oxidative status in normal platelets

BERMEJO, E; ALBERTO, F; SAENZ, DANIEL; BARI, S; LAZZARI, M; ROSENSTEIN, RUTH

Boston, USA

Congreso; XXII Congress of the International Society on Thrombosis and Haemostasis; 2009

PP-MO-038   EFFECT OF NYTROXYL AND NITRIC OXIDE ON THE OXIDATIVE STATUS IN NORMAL PLATELETS E. Bermejo*1, M. F. Alberto1, D. Saenz2, S. Bari3, M. A. Lazzari1, R. Rosenstein21Hemostasia y Trombosis, Instituto de Investigaciones Hematologicas Academia Nacional de Medicina, 2Departamento de Bioquímica Humana, Facultad de Medicina, Universidad de Buenos Aires, 3Departamento de Química Inorgánica, Analítica, Facultad de Ciencias, Buenos Aires, Argentina Abstract: Introduction: NO plays a key role in platelet physiology regulation. An alternative redox form of NO, namely nitroxyl (HNO) may be formed through diverse biochemical reactions. We have shown that HNO and NO significantly decreased platelet thiobarbituric acid reactive substances (TBARS) levels. An explanation for this result could be that these nitrogen-related species modify the platelet oxidative status. The aim of this work was to study the effect of HNO and NO on two key markers of oxidative mechanisms, such as reduced glutathione (GSH) and reactive oxygen species (ROS) levels. Methods: Human washed platelets (WP) from healthy volunteers were used throughout (300 x 109 WP/L). Angeli´s salt (AS) and sodium nitroprusside (SNP) were used as HNO and NO releasers, respectively. GSH and ROS levels were assessed by flow cytometry using mercury orange and 2´-7´- dichlorofluorescin diacetate (DCF), respectively, and results were expressed as the mean fluorescence intensities ± SE. (n=5)Results: Both SNP and AS (1 mM) significantly decreased GSH levels (control: 171±20, AS: 138. ± 4.4**, SNP: 129 ± 4.2**), whereas only AS significantly increased platelet ROS levels (control: 58 ± 2, AS: 83 ± .4**, SNP: 62 ± 3.2, (** p<0.01, ANOVA followed by Tukey´s test).Conclusions: These results suggest that HNO could regulate the platelet oxidative status by acting through a mechanism that partly overlaps with that involved in NO response. Although the effects of HNO were formerly explained by its conversion to NO, the fact that only AS (but not SNP) increased ROS levels supports that the effects of HNO cannot be merely attributable to its conversion to NO. Moreover, since glutathione is the major intracellular antioxidant, the decrease of GSH levels by both HNO and NO could lead to increased vulnerability to other oxidants. Thus, the effects of HNO and NO described herein may have branched consequences in platelet biochemistry.