BACKGROUND AND PURPOSE The ex vivo effect of aspirin (ASA) on platelet aggregation, the platelet component of thrombosis, was studied at repeated intervals in a cohort of patients taking aspirin for recurrent ischemic stroke prevention to define the maintenance of efficacy over time. METHODS We administered increasing doses of aspirin (from 325 to 1300 mg/d) to patients with previous ischemic...

FIVE MUCOPOLYSACCHARIDE STAINS INHIBIT PLATELET AGGREGATION INDUCED BY SEVERAL AGGREGATING AGENTS: with two stains inhibition is competitive. Alcian blue, 0.05 mg/ml, added to platelet-rich plasma potentiates ADP-induced aggregation. Alcian blue, 0.5 mg/ml, itself produces platelet aggregation, probably causing the release reaction. Three of these stains produce aggregation of red cells. They a...

We studied the role of adenosine (Ado), which is generated from adenine nucleotides via the activity of ecto-5*-nucleotidase (ecto-5*-NT), in the inhibition of platelet aggregation by endothelial cells (ECs). The enzymatic activity of nucleotidases on human umbilical vein endothelial cells (HUVECs) was examined with regard to (1) the inhibition of adenosine diphosphate (ADP)–induced platelet ag...

ADP is an important platelet agonist causing shape change and aggregation required for physiological hemostasis. We recently demonstrated the existence of two distinct G protein-coupled ADP receptors on platelets, one coupled to phospholipase C, P2Y1, and the other to inhibition of adenylyl cyclase, P2TAC. In this study, using specific antagonists for these two receptors, we demonstrated that c...

Defective regulation of platelet activation/aggregation is a predominant cause for arterial thrombosis, the major complication of atherosclerosis triggering myocardial infarction and stroke. A central regulatory pathway conveying inhibition of platelet activation/aggregation is nitric oxide (NO)/cyclic GMP (cGMP) signaling by cGMP-dependent protein kinase I (cGKI). However, the regulatory casca...

BACKGROUND It is still not clear whether native or platelet count adjusted platelet rich plasma (PRP) should be used for platelet aggregation measurements. AIM To evaluate the necessity of using adjusted PRP in platelet function testing. METHODS Platelet aggregation with native PRP and adjusted PRP (platelet count: 250/nl, obtained by diluting native PRP with platelet poor plasma) was perfo...

With the exception of the major platelet glycoproteins llb/Illa and lb. which function as receptors for fibrinogen and von Willebrand factor, little is presently known regarding the possible role of other platelet surface proteins in mediating platelet aggregation. We report the production of a murine monoclonal antibody (AG-i ) recognizing human platelet membrane surface protein of relatively ...

This study was designed to measure the magnitude and duration of inhibition of platelet aggregation following doses of aspirin or ibuprofen alone or taken in combination in a group of healthy volunteers. Ten normal volunteer subjects underwent 3 randomized treatment sessions: aspirin 325 mg alone, ibuprofen 400 mg alone, and ibuprofen 400 mg, followed by dosing with aspirin 325 mg 2 hours there...

Despite the fact that lysophosphatidic acid (LPA) has been identified as a main platelet-activating lipid of mildly oxidized low-density lipoprotein (LDL) and human atherosclerotic lesions, it remains unknown whether it is capable of activating platelets in blood. We found that LPA at concentrations slightly above plasma levels induces platelet shape change, aggregation, and platelet-monocyte a...

OBJECTIVE Unlike currently approved adenosine diphosphate receptor antagonists, the new diadenosine tetraphosphate derivative GLS-409 targets not only P2Y12 but also the second human platelet adenosine diphosphate receptor P2Y1 and may, therefore, be a promising antiplatelet drug candidate. The current study is the first to investigate the in vivo antithrombotic effects of GLS-409. APPROACH A...