Platelet aggregation induced in mice by whole-body hyperthermia

Whole-body hyperthermia ( WBH ) induced by 2450-MHz irradiation resulted in a decrease in platelet number in the circulating blood 3.5 hr after irradiation. Afterward, the treated mice developed thrombocytosis which peaked 3 days after WBH . This phenomenon was suppressed by administration of antiinflammatory drugs (methylprednisolone acetate and indomethacin) or aggregating inhibitors (heparin, pentoxifylline and dibutyryl cyclic AMP). These facts suggest that thrombocytosis occurring in treated mice arises to offset a deficiency of platelets induced by aggregations and adhesions. Further investigation of platelets in vitro indicated that the addition of plasma extract from mice treated with WBH to heated platelets induced a significant aggregation of platelets.