Studies on the interaction between manganese and fenitrothion in rats.

The effect of manganese pretreatment on acute toxicity of fenitrothion (FTH) was investigated in male rats by assessing the degree of enzymatic alterations. Oral administration of FTH (260 mg/kg) markedly inactivated cholinesterase (ChE) and carboxylesterase and elevated the activities of acid phosphatase, alanine aminotransferase and aspartate aminotransferase in different tissues 3 h after dosing. Pretreatment of rats with manganese (10 mg/kg, i.p.) 3 days prior to FTH application (260 mg/kg, p.o.) significantly enhanced these enzymatic changes. The results indicate that inhibition of esterases and elevation in other enzymes induced by manganese are likely to contribute to the increased enzymatic alterations observed following combined treatment.