What is the importance of platelet-activating factor?
What is the importance of platelet-activating factor?
Platelet-activating factor (PAF) is a potent phospholipid mediator that was first described by its ability to cause platelet aggregation and dilation of blood vessels. Now it is also known as a potent mediator of inflammation, allergic responses, and shock.
What stimulates platelet-activating factor?
PAF is produced by stimulated basophils, monocytes, polymorphonuclear neutrophils, platelets, and endothelial cells primarily through lipid remodeling. A variety of stimuli can initiate the synthesis of PAF. These stimuli could be macrophages going through phagocytosis or endothelium cells uptake of thrombin.
Where is platelet-activating factor located?
Platelet-Activating Factor Acetylhydrolases (PAF-AH) PAF-acetylhydrolase (PAF-AH) hydrolyzes the acetyl moiety of PAF at its sn-2 position and thereby inactivates it. PAF-AH Ib, originally identified in brain, exists in the cytoplasm of many (probably all) types of mammalian cells and tissues.
Is PAF vasoconstrictor or vasodilator?
We found that in the isolated microperfused rabbit afferent arteriole, PAF has a bi- phasic effect, inducing vasodilation at very low concentrations and vasoconstriction at higher concentrations. Both of these effects appear to be receptor mediated, since they were blocked by a specific PAF receptor antagonist.
Is Platelet-Activating Factor good?
The study of PAF and oxidized phospholipids catabolic enzyme, namely Lp-PLA2, also known as plasma platelet-activating factor acetylhydrolase) remains of great interest because of the contradictory aspects of being, or not, an independent marker of CVD risk due to its dual role in inflammation and oxidative stress20 …
Does platelet-activating factor cause vasodilation?
Platelet-activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent mediator of inflammation that causes neutrophil activation, increased vascular permeability, vasodilation, and bronchoconstriction in addition to platelet activation.
What type of lipid is platelet-activating factor?
Platelet-activating factor is identified as 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine12. Even though the majority of ether lipids has been replaced with their esterified analogs during evolution, PAF as some other phosphor glyceryl ether lipids were preserved due to their important biological roles12.
What is activation factor?
Biology To convert (a molecule or cell) into a form that carries out a specific action: activate an enzyme; activate B cells.
What is blood platelet aggregation?
Platelet aggregation, the process by which platelets adhere to each other at sites of vascular injury, has long been recognized as critical for hemostatic plug formation and thrombosis.
Where is prostacyclin produced?
Prostacyclin, a member of the endogenous prostanoids family, is produced from arachidonic acid in a multistep process involving the enzymes prostacyclin synthase and cyclooxygenase (COX). In the pulmonary circulation, prostacyclin is released by endothelial cells in the pulmonary artery.
How is the platelet activating factor ( PAF ) produced?
PAF is produced by a variety of cells, but especially those involved in host defense, such as platelets, endothelial cells, neutrophils, monocytes, and macrophages. PAF is continuously produced by these cells but in low quantities and production is controlled by the activity of PAF acetylhydrolases.
Why is platelet activating factor important to hemostasis?
Function. The pathway to apoptosis can be inhibited by negative feedback from PAF acetylhydrolase (PAF-AH), an enzyme that catabolizes platelet-activating factor. It is an important mediator of bronchoconstriction . It causes platelets to aggregate and blood vessels to dilate. Thus, it is important to the process of hemostasis.
What is the role of platelet activating factor in asthma?
Platelet-Activating Factor. Platelet-activating factor (PAF) is a potent inflammatory mediator that mimics many of the features of asthma, including eosinophil recruitment and activation and induction of AHR; yet even potent PAF antagonists, such as dominant, do not control asthma symptoms, at least in chronic asthma.
What kind of autocoid mediator is platelet activating factor?
Platelet-activating factor (PAF) is a potent autocoid mediator implicated in a diverse range of human pathologies including shock, ischemia, asthma, cardiac and systemic anaphylaxis, CNS and renal disorders, and a variety of inflammatory conditions.