A Dogs

Most dogs, mongrel or purpose-bred, have platelets that form TXA2, but foil to aggregate irreversibly or to secrete granular contents in response to the TXA2 formed (76). These TXA2 insensitive (TXAj-) platelets also fail to aggregate irreversibly or to secrete in response to TXA2 analogs such as U46619 or I-BOP (76). However, some mongrel dogs, and a few purpose-bred strains of dogs, have TXA2 sensitive (TXAj+) platelets that aggregate and secrete in response to the TXA2 formed as do human...

Dplatelet Tp Receptor Desensitization

Desensitization of TP receptor-mediated platelet activation has been studied extensively. Liel, et al (154) and Murray and FitzGerald 155) carried out the first studies of homologous desensitization of normal TP receptors. They observed that exposure of platelets to TP receptor agonists resulted in attenuation of subsequent agonist-induced platelet aggregation and a reduction in receptor sites identified by radioligand binding. Okwu, et al (107) found that shape change, as well as aggregation,...

Platelet physiology

Physiological agonists cannot penetrate the plasma membrane barrier and therefore, they must first couple to specific interactive domains on the platelet surface membrane in order to trigger the sequence of activation signals (21 -29, reviewed by Ryningen and Holmsen in this book). The physiological agonists that are known to activate platelets include adenosine diphosphate (ADP), epinephrine (adrenaline), thromboxane A2 (Txj ), thrombin, and platelet activation factor (PAF). In addition, cell...

Table 1 Antiplatelet Antithrombotic drugs

Acetyl salicylic acid (aspirin), Nonsteroidal antiinflammatory drugs (NSAID), Phenylbutazone, Indomethacin, Ibuprofen, Fenoprofen, Fluriboprofen, Neproxen, Sulfinpyrazone, antioxidants (Butylated Hydroxytoluene, BHT Butylated Hydroxyanisole, BHA Dipheylamine, DPA). Benzydamine, Imidazole congeners, 9, ll-azo-13 oxa-15 hydroxy prostanoic acid, 9, ll-azoprosta-5-13 dienoic acid (U-51605), 9, ll(epoxmethano) prostanoic acid, l(isopropyl-2-indloy (l)-3 pyridyl-3-ketone (L-8027)....

Acknowledgements

Anupama R. Tate and Dr. Mahadev Murthy for their help in the preparation of this manuscript. This work was supported by grants from NIH HL-18880, Laboratory Medicine & Pathology and Biomedical Engineering Institute. 1. Marcus AJ, Zucker MB. The physiology of blood platelets. New York Crane and Scrutton, 1965. 2. Kowalski E, Niewiarowski S. Biochemistry of blood platelets. New York Academic Press, 1966. 3. Caen J. Platelet aggregation. Paris Masson and...