Effects of dichlorvos and characterization of microsomal NADPH-cytochrome P450 and NADH-ferricyanide reductase in rainbow trout (Oncorhynchus mykiss) liver

Abstract

The kinetics of oxidation of rainbow trout (Oncorhynchus mykiss) NADPH-cytochrome P450 reductase (NCPR) by cytochrome-c and NADH-ferricyanide reductase (NFR) by K3Fe(CN)(6) were studied. NCPR and NFR activities from liver microsomes of rainbow trout (Oncorhynchus mykiss) had a specific activity of 0.0246 and 0.0350 nmoles/min/mg protein, respectively. The maximal rate of NCPR reaction was found at cytochrome-c concentrations above 2.1 mM and in the presence of cyt c. V-max and K-m were 0.0083 nmoles/min/mg and 1.14 mM. The maximal rate of NFR reaction was at K3Fe(CN)6 concentrations higher than 2.0 mM and in the presence of K3Fe(CN)(6). V-max and K-m values were 1.04 nmoles/min/mg and 0.352 mM, respectively. The inhibition by dichlorvos (DDVP) on NCPR and NFR activity was not exhibited over the range 1.0-5.0 mM DDVP.