A STUDY ON RAT PLATELET RESPONSIVENESS FOLLOWING INTRAVENOUS ENDOTOXIN ADMINISTRATION

The aim of the present study was to evaluate platelet responsiveness i n rats following E. coli endotoxin administration. Injection of E. col i to rats caused a reduction in ADP-induced pulmonary In-111 labelled platelet accumulation four hours later. Similarly, when platelet aggre gation was evaluated on PRP obtained from rats four hows after endotox in administration we found that platelet response to both ADP and coll agen was significantly reduced. When platelets obtained from endotoxem ic rats were suspended in normal plasma, the aggregating response to A DP and collagen was not different from that obtained with control plat elets. Similarly, platelets from control rats suspended in plasma from endotoxemic rats showed hyporesponsiveness to ADP and collagen. There was no difference in the aggregatory response to collagen or to throm bin of washed platelet suspension (WPS) obtained from endotoxemic and normal rats. In conclusion, by using an in vivo minimally invasive tec nique and an ex vivo platelet aggregation test we demonstrate that dur ing endotoxemia platelet are functionally unaltered and the platelet h yporesponsiveness is only observed in presence of plasma.