Thursday, November 5, 2009: 4:40 PM
Kohlberg (Camino Real Hotel)
The plasma membrane Ca2+ ATPase (PMCA) modulates cytosolic calcium concentrations. PMCA activity was evaluated as native and in presence of calmodulin (CaM). Activities of PMCA were evaluated in a broad range of Cypermethrin, and Deltamethrin (0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mM), at low concentrations both pyrethroids activated PMCA activity, but at high concentration both of them inhibited nearly all the PMCA activity. To explore the potential protection of CaM the same assays were evaluated including CaM in the experiments, in these conditions Deltamethrin fully inhibited at all concentrations tested; but Cypermethrin activation and inhibition trend was not changed. These experiments suggest that CaM and Deltamethrin compete for the binding site of PMCA. To further investigate the effect of Cypermethrin, Km(app) were evaluated by using Cypermethrin constant (0.05mM) and ATP as variable substrate and CaM as protector. The results showed that CaM alone increased Km(app) but Km(app) in presence of Cypermethrin was nearly the same as the one.