Effect of insecticides and inhibitors on P-glycoprotein ATPase (M-type) activity of resistant pest Helicoverpa armigera

P-glycoprotein (P-gp) was detected using C219 antibodies from the membrane preparation of the insecticide resistant pest, Helicoverpa armigera. This protein was partially purified and found to be a glycoprotein having ATPase activity. Its molecular mass as determined by SDS–PAGE was 150 kDa. Insecticides, viz. monocrotophos, endosulfan, cypermethrin, fenvalerate and methyl parathion stimulated P-gp ATPase activity. Orthovanadate at 1.5 μM concentration inhibited P-gp ATPase activity by 70%, whereas HgCl2 and PCMBS at 200 μ μM inhibited it by 75 and 70% respectively. EDTA and sodium azide inhibited P-gp ATPase activity by 20% at 0.5 and 2μ μM respectively, and sodium molybdate (10 μM) did not inhibit P-gp ATPase activity.