Lactate Dehydrogenase Activity: Effect in vitro of Some Pesticidal Chemicals

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Science  30 Dec 1966:
Vol. 154, Issue 3757, pp. 1661-1662
DOI: 10.1126/science.154.3757.1661


The effect of chlorinated hydrocarbon insecticides upon rabbitmuscle lactate dehydrogenase was determined by both the direct determination of diphosphopyridine nucleotide reduction and a tetrazolium salt reduction method. A comparison of the two assay procedures revealed that the pronounced stimulation of lactate dehydrogenase LDH activity was noted with the tetrazolium salt method but could not be detected with a direct photometric determination method. Incubation of lactate dehydrogenase with DDT or heptachlor prior to the addition of either diphosphopyridine nucleotide or substrate resulted in a complete inhibition of enzyme activity. The inclusion of either diphosphopyridine nucleotide or substrate in the prior incubation mixtures afforded no protection to the enzyme.