[The effect of dichlorvos and metathion on selected enzymes of the amoeba Tetrahymena pyriformis].

The effect of dichlorvos and metathion was studied as exerted on acetylcholinesterase activity in the protozoan Tetrahymena pyriformis. In dichlorvos, the highest enzyme activity inhibition was obtained after 30 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 1.22 mg per litre. As to metathion, the highest enzyme activity inhibition was obtained after 60 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 879.2 ng per litre. One hour after exposure to this dose, almost 75% inhibition of the activity of the enzyme was recorded. The determination of acetylcholinesterase activity increases the sensitivity of the bioassay for organophosphates with the use of the Tetrahymena pyriformis protozoan. Dichlorvos was studied for its action at supratoxic doses (50.0, 100.0 and 150.0 mg per litre) and it was found that lactate dehydrogenase activity was almost completely suppressed; the inhibition of alanine aminotransferase was pronounced. A weaker activity inhibition was recorded in aspartate aminotransferase, alkaline and acid phosphatase; the activity of alpha-amylase increased. No dependence on dosage was demonstrated.