Generation of reactive oxygen species in blood platelets

Abstract

The generation of superoxide anion radicals (O2*-) and the other reactive oxygen species (ROS) was estimated by means of cytochrome c reduction and chemiluminescence, as well in resting blood platelets and in platelets stimulated by thrombin in the presence or absence of some inhibitors of pathways involved in platelet activation. We used allopurinol (xanthine oxidase inhibitor), wortmannin (PI 3-kinase inhibitor) and staurosporine (protein kinase C inhibitor). To determine the involvement of the glutathione in ROS generation, we used L-buthionine sulfoximine (BSO) which blocks GSH synthesis. Our results confirmed that thrombin stimulates the production of ROS concomitant with metabolism of arachidonate and production of malonyldialdehyde (MDA) in blood platelets (P < 0.05) and showed that, in the presence of inhibitors, the generation of ROS in platelets (resting and stimulated) was reduced. This indicates that xanthine oxidase, PI 3-kinase or protein kinase C take part in the formation of ROS in blood platelets. Moreover, adhesion of platelets to fibrinogen and secretion of adenine nucleotides from platelets after wortmannin and staurosporine action was also inhibited. BSO not only decreased GSH level, but also reduced the amount of ROS; a correlation between the depletion of GSH and the decrease of ROS was observed (R = -0.987; P < 0.02). It is concluded that in blood platelets, ROS are produced in the receptor-mediated signaling pathways and platelet activation (arachidonic acid metabolism, the glutathione cycle, metabolism of phosphoinositoides and due to xanthine oxidase). Our results support the importance of ROS in platelet function.

Glucose and collagen regulate human platelet activity through aldose reductase induction of thromboxane

“…Interestingly, ROS derived from platelet activation also plays an important role in signaling upon collagen-induced platelet aggregation. Free radical species act as secondary messengers that increase cytosolic Ca 2+ during the initial phase of platelet activation processes, and PKC is involved in receptor-mediated ROS production in platelets (36). Previous studies also showed that ROS formation is involved in collageninduced platelet aggregation, which is dependent on AA release and its metabolism (34); thus, ROS may be needed for platelet activation (37).…”

“…Glucose flux through AR is well recognized to generate oxidative stress by several mechanisms, including NADPH depletion, decreasing glutathione (GSH) levels (NADPH is the cofactor for GSH reductase that regenerates GSH from GSH disulfide [GSSG]), and increasing advanced glycation end products, generating ROS (10). Previous studies have demonstrated that TXA 2 biosynthesis is upregulated by oxidant formation (e.g., hydrogen peroxide) during platelet aggregation (34)(35)(36). We and others (16,20) have demonstrated that hyperglycemia increases oxidative stress in platelets.…”

Effect of l-Carnitine on Acetyl-CoA Content and Activity of Blood Platelets in Healthy and Diabetic Persons

“…In platelets, MDA is synthesized from arachidonic acid in equivalent amounts with thromboxane A 2 and derived thomboxane B 2 (25,30 ). However, much greater amounts of MDA are formed in peroxidation processes of other platelet lipids (31 ).…”

An investigation of the antiplatelet effects of succinobucol (AGI-1067)

“…However, the direct effects of reactive oxygen species (ROS) on platelets are inconsistent with previous studies reporting both pro-and anti-aggregatory effects when platelets are exposed to exogenous ROS [15]. Oxidant stress generated either by platelets themselves via several intracellular sources [16] or by the artery wall can also modulate vascular tone [17] and this has implications for blood flow and thrombus formation within blood vessels.…”