The C-terminal segment of the second extracellular loop of the thromboxane A2 receptor plays an important role in platelet aggregation

2012 ◽  
Vol 83 (1) ◽  
pp. 88-96 ◽  
Author(s):  
John P. Murad ◽  
Enma Veronica Paez Espinosa ◽  
Harold J. Ting ◽  
Fadi T. Khasawneh
Keyword(s):  
Platelet Aggregation ◽  
Thromboxane A2 ◽  
Terminal Segment ◽  
Extracellular Loop ◽  
Thromboxane A2 Receptor

The Endocannabinoid 2-Arachidonoylglycerol Regulates Platelet Function.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3904-3904
Author(s):  
Samantha Baldassarri ◽  
Alessandra Bertoni ◽  
Paolo Lova ◽  
Stefania Reineri ◽  
Chiara Sarasso ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Platelet Function ◽  
Cannabinoid Receptors ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Dependent Manner ◽  
Cb2 Receptor ◽  
Thromboxane A2 Receptor

Abstract 2-Arachidonoylglycerol (2-AG) is a naturally occurring monoglyceride that activates cannabinoid receptors and meets several key requisites of an endogenous cannabinoid substance. It is present in the brain and hematopoietic cells, including macrophages, lymphocytes and platelets. 2-AG is released from cells in a stimulus-dependent manner and is rapidly eliminated by uptake into cells and enzymatic hydrolysis in arachidonic acid and glycerol. 2-AG might exert a very fine control on platelet function either through mechanisms intertwining with the signal transduction pathways used by platelet agonists or through mechanisms modulating specific receptors. The aim of this study was to define the role of 2-AG in human platelets and characterize the mechanisms by which it performs its action. Platelets from healthy donors were isolated from plasma by differential centrifugations and gel-filtration on Sepharose 2B. The samples were incubated with 2-AG (10–100 μM) under constant stirring in the presence or absence of various inhibitors. Platelet aggregation was measured by Born technique. We have found that stimulation of human platelets with 2-AG induced irreversible aggregation, which was significantly enhanced by co-stimulation with ADP (1–10 μM). Furthermore, 2-AG-dependent platelet aggregation was completely inhibited by ADP scavengers, aspirin, and Rho kinase inhibitor, as well as by antagonists of the 2-AG receptor (CB2), of the ADP P2Y12 receptor, and of the thromboxane A2 receptor. We further investigated the role of endocannabinoids on calcium mobilization. Intracellular [Ca2+] was measured using FURA-2-loaded platelets prewarmed at 37°C under gentle stirring in a spectrofluorimeter. 2-AG induced rapid increase of cytosolic [Ca2+] in a dose-dependent manner. This effect was partially blocked by ADP scavengers and CB2 receptor antagonists. Furthermore, 2-AG-induced [Ca2+] mobilization was totally suppressed by aspirin or the thromboxane A2 receptor antagonist. These results suggest that 2-AG is able to trigger platelet activation, and that this action is partially mediated by CB2 receptor and ADP. Furthmore, 2-AG-dependent platelet activation is totally dependent on thromboxane A2 generation.

The Effect of Inhaled Anesthetics on the Platelet Aggregation and the Ligand-Binding Affinity of the Platelet Thromboxane A2 Receptor

1995 ◽  
Vol 81 (1) ◽  
pp. 114-118
Author(s):  
Hideo Hirakata ◽  
Fumitaka Ushikubi ◽  
Shuh Narumiya ◽  
Yoshio Hatano ◽  
Kumi Nakamura ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ligand Binding ◽  
Binding Affinity ◽  
Thromboxane A2 ◽  
Thromboxane A2 Receptor ◽  
Inhaled Anesthetics ◽  
Platelet Thromboxane

The Effect of Inhaled Anesthetics on the Platelet Aggregation and the Ligand-Binding Affinity of the Platelet Thromboxane A2 Receptor

1995 ◽  
Vol 81 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Hideo Hirakata ◽  
Fumitaka Ushikubi ◽  
Shuh Narumiya ◽  
Yoshio Hatano ◽  
Kumi Nakamura ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ligand Binding ◽  
Binding Affinity ◽  
Thromboxane A2 ◽  
Thromboxane A2 Receptor ◽  
Inhaled Anesthetics ◽  
Platelet Thromboxane

scholarly journals Inhibitory Effect of Ethanol Extract of Piper longum L. on Rabbit Platelet Aggregation through Antagonizing Thromboxane A2 Receptor

2007 ◽  
Vol 30 (7) ◽  
pp. 1221-1225 ◽  
Author(s):  
Masaya Iwashita ◽  
Masaki Saito ◽  
Yasunaga Yamaguchi ◽  
Ryoji Takagaki ◽  
Norimichi Nakahata
Keyword(s):  
Platelet Aggregation ◽  
Thromboxane A2 ◽  
Ethanol Extract ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Piper Longum ◽  
Thromboxane A2 Receptor
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