Binding of insecticides to serum proteins in mosquitofish (Gambusia affinis)

Incubation of various organochlorine insecticides with mosquitofish serum leads to their association with, primarily, the vitellogenin/lipoprotein and albumin fractions. A significant variation in the quantity of each insecticide bound in the particular fractions was observed. Binding appeared to increase with compounds of increasing polarity, suggestive of protein binding. Preincubation of serum with endrin or aldrin significantly reduced the quantity of [3H]DDT subsequently bound while the reverse was not observed. Although the reason for the apparent quantitative decrease in binding is unknown, the reduction in binding of a particular xenobiotic, due to the presence of a second, has serious toxicological implications.