Platelets release reaction

Dismption of the endothehal surface of blood vessels expose coUagen fibers and connective tissue. These provide surfaces that promote platelet adherence, platelet release reaction, and subsequent platelet aggregation. Substances Hberated from the platelets stimulate further platelet aggregation, eg, adenosine diphosphate maintain vasoconstriction, eg, serotonin and participate in blood coagulation, eg, platelet Factors III and IV. In addition, the release reaction modifies platelet membranes in a manner that renders phosphoHpid available for coagulation. The thrombin [9002-04-4] elaborated by the coagulation mechanism is a potent agent in the induction of the platelet release reaction. 

F. Role in therapy The potential advantages of Angiomax—a direct thrombin inhibitor—over heparin include activity against clot-bound thrombin, more predictable anticoagulation, and no inhibition by components of the platelet release reaction. The place in therapy of Angiomax will be determined by further comparisons with heparin, low-molecular weight heparins, and recombinant hirudin. 

Rendu F, Brohard-Bohn B. 2001. The platelet release reaction Granules constituents, secretion and functions. Platelets 12 261-273. 

HOLMSEN H, Day H J. The selectivity of the thrombin-induced platelet release reaction subcellular localization of released and retained constituents. JClin Med 75 840-855,1970. 

Zahavi J, Price AJ, Kakkar W. Enhanced platelet release reaction associated with general anaesthesia. Lancet 1980 l(8178) 1132-3. 

Rendu F, Daveloose D, Debouzy JC, BourdeauN, Levy-Toledano S, Jain MK, Apitz-Castro R. Ajoene, the antiplatelet compound derived from garlic, specifically inhibits platelet release reaction by affecting the plasma membrane internal microviscosity. U 150 INSERM, URA 184 CNRS, Hopital Lariboisiere, Paris, France. 

The choice of which enzyme to monitor is important. Some workers prefer to select Factor Xa because it does not react with fibrinogen or cause the platelet release reaction as thrombin does. Wahl and co-workers prefer to test for thrombin activity since they found S-2238 to be more sensitive than S-2222 (W6). This objection could be overcome by using a substrate (S-2337) which is claimed to be more sensitive for Factor Xa (S16). As of now, the synthetic substrate assay for PF4 is unlikely to replace the radioimmunoassay because of lower sensitivity. 

Gorman, R.R., Wierenga, W. and Miller, O.V. (1979). Independence of the cyclic AMP-lowering activity of thromboxane A2 from the platelet release reaction. Biochim. Biophys. Acta, 572, 95-104... 

These data indicated that platelets may exhibit two mechanisms for serotonin release because under the condition of maximal inhibition by aspirin further release of serotonin could be elicited by raising connective tissue particle concentration. Based solely on the relative inhibition of l C-serotonin release, Indomethacin was found to be more potent than aspirin. The release of platelet factor 4, heparin neutralizing activity (HNA), in response to exogenous ADP is Inhibited by aspirin.20 Both the formation of initially formed platelet bound MA and the release of soluble HNA associated with the platelet release reaction are blocked by aspirin. Aspirin also inhibited the release of platelet factor 3 from human platelets Induced by ADP. Platelet factor 3 release appears to depend on the degree of aggregation and does not parallel the release of serotonin or endogenous ADP.21... 

The endothelium can interact with circulating platelets in at least two ways. First of all, products of the platelet release reaction (i.e. ADP and serotonin) have been shown to be potent stimulators of endothelium-derived relaxing factor (i.e. NO). The second mechanism involves a direct and potent... 

Recently, we have explored the effect of DDA on another secretory system, such as the platelet release reaction and aggregation response. In these studies we found that DDA, by itself, has no effect on both platelet aggregation and PF4 release induced by several stimuli (ADP,... 

Miscellaneous Agents - It has been reported that high concentrations of penicillin 6 are capable of inhibiting ADP, collagen and thrombin induced PA as well as the platelet release reaction in human PRP and in suspensions of washed platelets from rabbits or pigs.26... 

Studies on the mechanism of the human platelet release reaction induced by immunological stimuli. 

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