Platelet reactivity, effect plasma

When each of the acrylate or methacrylate polymers was preincubated with whole plasma, the platelet reactivity of the surfaces upon subsequent exposure to whole blood decreased significantly (Fig. 3). On the other hand, with many other polymers this effect of plasma was not seen. Of 20 varieties of segmented polyurethanes examined, none showed this behavior (22), and platelet adhesion to polystyrene was also unaffected by plasma pretreatment ( ). The phenomenon of plasma-induced passivation of methacrylate and acrylate polymers presumably involves selective adsorption of specific plasma proteins by the surfaces and/or a particular alteration of the adsorbed protein once bound. 

Dipyridamole reversibly inhibits platelet phosphodiesterase (see Fig. 28.3) and in consequence cyclic AMP concentration is increased and platelet (thrombotic) reactivity reduced evidence also suggests that its antithrombotic effect may derive from release of prostaglandin precursors by vascular endothelium. Dipyridamole is extensively bound to plasma proteins and has a t/ of 12 h. 

Fig. 2.4 Diagram showing the effect of ischemic injury on glycerophospholipid-derived iipid mediators in brain. Plasma membrane (PM) iV-methyl-D-aspartate receptor (NMDA-R) giuteimate (GIu) phosphatidylcholine (PtdCho) lyso-phosphatidylcholine (lyso-PtdCho) cytosolic phospholipase A2 (CPLA2) secretory phospholipase A2 (SPLA2) cyclooxygenase (COX-2) arachidonic add (ARA) platelet-activating factor (RAF) 4-hydroxynonenal (4-HNE) reactive oxygen species (ROS) nuclear factor kappaB (NF-kB) nuclear factor kappaB response element (NF-kB-RE) inhibitory subunit of NFkB (IkB) tumor necrosis factor-a (TNF-a) interleukin-ip (IL-ip) interleukin-6 (IL-6) matrix metaUoproteinases (MMPs) positive sign (+) represents upregulation...

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