Evidence for an Interaction between p-Glycoprotein and Cadmium Toxicity in Cadmium-Resistant and -Susceptible Strains of Drosophila melanogaster

The role of an ATP-dependent membrane protein, p-glycoprotein (pgp), in cadmium toxicity and resistance in Drosophila melanogaster was investigated. Two strains were compared, a wild-type and a cadmium-resistant strain. Verapamil (1, 10, and 100 μM) was added to the larval diet of Drosophila in both the presence and the absence of 80ppm cadmium chloride. Adult emergence of wild-type but not of cadmium-resistant flies was reduced in the presence of cadmium. Verapamil in the larval diet without cadmium had no effect on adult emergence in either strain. Verapamil in the diet spiked with cadmium significantly reduced adult emergence in both strains. This result is indicative of an interaction between the efflux of cadmium and verapamil and demonstrates that pgps have a role in regulating the toxicity of cadmium in Drosophil. These results do not rule out pgps as putative cadmium resistance genes.