Thrombin aggregating agent

The test compound is administered 2 h after platelet injection concurrently with the fourth administration of the aggregating agent. Thirty minutes (ADP, PAF, arachidonic acid, thrombin), or 1 h (collagen) after compound administration another control injection of the aggregating agent is given. This injection is either used as an additional control or it may reveal long-term efficacy of a test compound. 

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. 

Thrombin and other agents cause platelet aggregation, which involves a variety of biochemical and morphologic events. Stimulation of phosphofipase C and the polyphosphoinositide pathway is a key event in platelet activation, but other processes are also involved. 

Both cyclo(Gly-Tyr) and cyclo(Gly-Phe)significantly inhibited ADP- and thrombin-induced aggregation of isolated platelets. Both DKPs displayed efficacy as antibacterial agents against several bacterial cultures... 

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