Toxicity of Cypermethrin and Fenitrothion on the Hemolymph Carbohydrates, Head Acetylcholinesterase, and Thoracic Muscle Na+, K+-ATPase of Emerging Honeybees (Apis mellifera mellifera. L)

Organophosphorus (OP) compounds have been reported to inhibit Ca/Mg-ATPase, but the relevance of this inhibition to organophosphate-induced delayed neuropathy (OPIDN) has not been explored. To determine if inhibition of this enzyme was related to the development of OPIDN, neuropathic and nonneuropathic OP compounds were tested for their ability to inhibit Ca-stimulated ATPase activity in the P2 synaptosomal fraction from hen brain. Following in vitro exposure to 10-3 to 10-5 M OP compounds, Ca-stimulated ATPase activity was inhibited by chlorpyrifos, chlorpyrifos-oxon, phenyl saligenin phosphate (PSP), and tri-o-tolyl phosphate (TOTP), but not by parathion, paraoxon, or diisopropyl fluorophosphate (DFP). Further investigation of inhibition induced by chlorpyrifos determined that inhibition was noncompetitive with respect to calcium and ATP. OP compound hydrophobicity was well correlated with in vitro inhibition of Ca-stimulated ATPase, suggesting that OP compounds interact with membrane lipids, and this i...

Ashlesha A. Deshpande

Papers

The kinetics of methylparathion and fenvalerate action and Ca2+ antagonism on the activity of (Ca2+ + Mg2+)-ATPase in sorghum (Sorghum bicolor L.)