Aldrin Epoxidase Activity in Developing Rabbit Lung

Abstract

SummaryPulmonary aldrin epoxidase activity was determined in 2-, 4, 6 , &, I t , and ldweek-old male rabbits using isolated perfused lung preparations and in vim incubation techniques. In the perfusion experiments, it was determined that aldrin epoxidase activity increased with age up to 12 weeks of age. Although there was an increase in the weight of lungs with age, this did not appear to be related to the increase in aldrin epoxidation. In vim experiments carried out using the same substrate to tissue ratio failed to exhibit an age-related increase in the aldrin epoxidase activity. Extrapolated values for aldrin epoxidation from in vibw experiments yielded much higher values than realized from perfusion experiments. Accessibility of the substrate to the enzymatic sites, saturation of the accessible e v e system, and limiting availability of the cofactor necessary for the oxidative reaction remain as the possible mechanisms for the discrepancy between perfusion and in vim incubation studies. SpeculationPulmonary aldrin epoxidase activity determined using isolated perfused lung preparations does not correlate with in vim results obtained from incubations fortified with cofactors. However, the ratio of the two may become a useful predictive factor to obtain realistic contribution of an organ to the metabolism of xenobiotics.