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FACTORS INFLUENCING DIISOPROPYL FLUOROPHOSPHATE-INDUCED HYPOTHERMIA AND HYPERTHERMIA IN THE RAT
Citation:
Gordon, C. FACTORS INFLUENCING DIISOPROPYL FLUOROPHOSPHATE-INDUCED HYPOTHERMIA AND HYPERTHERMIA IN THE RAT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-96/043.
Description:
Exposing rats to the anticholinesterase (antiChE) diisopropyl fluorophosphate (DFP) causes a transient hypothermia lasting approximately 24 hours followed by a period of hyperthermia lasting approximately 48 hours. ince a fever is a predominant thermoregulatory response in humans exposed to antiChE pesticides, the hyperthermic response in the rat may be important to understanding the central neural mechanisms of antiChEs. he purpose of the present study was to assess the dependence of DFP-induced thermoregulatory changes on basal behavioral and autonomic activity in the rat. ore temperature (TC), heart rate (HR), and motor activity (MA) were monitored via radiotelemetry in unrestrained rats 24 hr prior to and 72 hr after administration of the peanut oil vehicle or 1.5 mg/kg DFP. orrelations between DFP-induced hypothermia and hyperthermia with baseline TC/ HR, and MA were performed. he baseline Tc was inversely correlated with the magnitude of DFP-induced hyperthermia (r 2=0 .6). FP-induced hyperthermia was also inversely correlated with baseline HR and MA. he minimum core temperature during DFP-induced hypothermia was directly correlated with the baseline Tc, The inverse pattern between baseline Tc and DFP-induced hyperthermia is similar to that of rats administered endotoxin and other pyrogenic agents. 60% of the variation in DFP-induced hyperthermia, a toxic response seen >48 hr after exposure, can be explained by individual differences in baseline Tc, This relationship may be important in understanding the thermoregulatory and metabolic effects of antiChE agents.