Effect of paraquat (methyl viologen) on liver function in mice.

Paraquat poisoning may result in pulmonary damage and hepatotoxicity. To examine the effect of paraquat on liver function, paraquat-treated mice were injected with sulfobromophthalein (BSP, 100 mg/kg) or indocyanine green (20 mg/kg) via the tail vein and plasma concentrations of these compounds were determined at various times. Hepatic concentrations of reduced glutathione were also determined following paraquat. Retention of BSP and indocyanine green in the plasma was observed 24 hours after paraquat. Body temperature of the poisoned mice was significantly depressed 24 hours after treatment and the paraquat-induced indocyanine green retention could be reversed by warming the paraquat-treated mice to normal body temperature. In contrast, paraquat-induced BSP retention was independent of body temperature. Inasmuch as hepatic glutathione concentrations were reduced 24 hours after paraquat treatment, the retention of BSP in the plasma may have been secondary to the reduction of hepatic glutathione concentrations.