Influence of pregnancy on the hepatic metabolism of parathion

The effect of pregnancy on the hepatic metabolism of parathion was examined. The in vitro rate of hepatic microsomal activation of parathion to paraoxon was significantly reduced in mice at 19 days of gestation when compared to nonpregnant controls. Total hepatic metabolism of parathion was determined during in situ perfusion of livers from pregnant and nonpregnant mice. Levels of parathion, paraoxon, and p-nitrophenol in the perfusate after 45 min of perfusion did not differ significantly between livers from the pregnant and nonpregnant groups. These data indicate that total hepatic metabolism of these three compounds is not altered in pregnancy despite a decrease in specific activity for parathion activation.