Accumulation of blood platelets in carrageenin rat paw oedema. Possible role in the inflammatory process.

The accumulation of blood platelets in the carrageenin-induced paw oedema in rats was studied, using 51Cr-labeled platelets. A maximum in the accumulation was seen after 4 hours, followed by a decline after 5--6 hours. During the first 6 hours of the oedema formation, change in blood volume were small. A comparison was made with the accumulation of both 125J-albumin as a measure of extravasation and 125J-fibrinogen as an indication of blood clotting. When platelet aggregation was measured during the first 6 hours of the oedema formation, the lag time between the addition of collagen and the beginning of the aggregation was increased. No change in platelet serotonin was seen. These data support the idea that platelets participate in the inflammatory process.