In vitro pesticide inhibition of muscle esterases of the mosquitofish, Gambusia affinis

Abstract 1. The in vitro inhibition of Gambusia affinis muscle esterases by various pesticides was investigated. 2. The oxygen analogs of several organophosphates were found to be potent inhibitors of muscle esterases. 3. Analytically pure malathion did not inhibit esterases unless preincubated with muscle extracts prior to electrophoresis. 4. It is suggested that extracts of muscle have some capability of malathion degradation.