Characterization of Canine Platelet Activation Induced by Platelet Activating Factor (PAF)

Abstract

ABSTRACT. Characteristics of the signal transduction in Platelet activating factor (PAF)-activated platelets and effects of anti-platelet agents on this response were investigated in vitro for potential therapeutic applications in canine endotoxemia. Blockade of the PAF receptor by a specific blocker has the strongest inhibitive effect on the PAF-induced platelet reactions. The response was also inhibited by either Ca 2+ channel blockers or prostaglandin E 1 .KEY WORDS: canine platelet, inhibitor, platelet activating factor.

Embolic-Thrombotic Complications in Dogs in The Course of Endotoxaemia

“…In dogs with endotoxaemia, respective reports documented alterations in the clotting cascade and fibrinolysis, in the forms of thrombocytopoenia, DIC, extended partial thromboplastin and prothrombin time, and formation of intravascular thrombi (8,9). In presented cases of dogs with endotoxaemia, numerous embolic-thrombotic disturbances were detected, frequently causing death of an animal.…”

“…Nevertheless, microthrombi and microemboli in the lungs or heart may lead to severe complications, including death (4). Causes and the mechanism of the phenomenon have not been fully clarified (8). Endotoxaemia is known to lead to thrombocytopenia, secondary to platelet activation and exacerbation of the endotoxin-induced DIC (8).…”

“…Causes and the mechanism of the phenomenon have not been fully clarified (8). Endotoxaemia is known to lead to thrombocytopenia, secondary to platelet activation and exacerbation of the endotoxin-induced DIC (8). Nevertheless, LPS alone are not able to induce platelet activation in vivo, and a certain role in platelet activation is ascribed to platelet activating factor (PAF), von Willebrand's factor, and P-selectin, which is expressed on activated cells of endothelium and on blood platelets (7,8).…”

“…The most common diseases accompanied by endotoxaemia in domestic animals include myometra, severe bacterial infections induced by Pseudomonas sp., Staphylococcus sp., or Escherichia coli, and gastric volvulus (2)(3)(4). Animals with severe infections, induced by Gram-negative bacteria, tend to develop disturbances in clotting cascade but mechanism of the phenomenon has not been sufficiently clarified (8). Dogs with endotoxaemia were noted to develop thrombocytopoenia, disseminated intravascular coagulopathy (DIC), extended partial thromboplastin time and prothrobin time, and formation of intravascular thrombi (8,9).…”

“…Animals with severe infections, induced by Gram-negative bacteria, tend to develop disturbances in clotting cascade but mechanism of the phenomenon has not been sufficiently clarified (8). Dogs with endotoxaemia were noted to develop thrombocytopoenia, disseminated intravascular coagulopathy (DIC), extended partial thromboplastin time and prothrobin time, and formation of intravascular thrombi (8,9). Organs particularly sensitive to the consequences of embolic-thrombotic disturbances include the brain, heart, and kidneys while damage to the organs resulting from endotoxaemia frequently lead to death of the animal (2,3).…”