Effects of acute paraquat toxicity on circulating levels of arachidonic acid, PGF2α and PGE2 in the beagle

We studied the effects of paraquat (25 mg/kg, free base, I.V.) on the circulating plasma levels of arachidonic acid, PGF2a and PGE2 in the beagle. The arachidonic acid level was quantified by GLC and prostaglandins by radioim unoassay.The plasma levels of arachidonic acid after paraquat treatment were decreased to 50.8% of control at 0.5 hrs. Thereafter the levels increased with time reaching a maximum level of 127.8% at 12 hrs, from which it decreased to 82.8% of control at 24 hrs. Concurrent with these changes in arachidonic acid, the plasma PGE₂ levels at 0.5, 1.5, 6.0, 12.0 and 24.0 hrs were significantly decreased to 65.4%, 42.5%, 52.4%, 41.0% and 50.3% of control levels, respectively. In contrast to these findings the plasma levels of PGF2a after paraquat treatment were insignificantly elevated at 0.5, 3.0, 6.0, 12.0, and 24.0 hrs, to 174.3%, 170.4%, 119.3%, 183.3% and 180.3% of control respectively. The ratio of PGE₂/PGF_2α exhibited a significant decrease at 12.0 and 24.0 hrs. Histopathological studies revealed insignificant changes of the lungs, but marked changes of the kidney. We concluded from these studies that changes in plasma levels of prostaglandins may be related to the acute nephrotoxicity caused by paraquat in dogs.