Selective inactivation of rat lung and liver microsomal NADPH-cytochrome c reductase by acrolein

Addition of acrolein to rat lung or liver microsomal suspensions resulted in total inactivation of NADPH-cytochrome c reductase and partial conversion of cytochrome P-450 to P-420 in a concentration- and time-dependent fashion. Acrolein also caused total loss of nonprotein sulfhydryl content in both preparations, whereas protein sulfhydryl content was decreased by 40% and 28% in lung and liver preparations, respectively. Maxima of about 60% of the total lung cytochrome P-450 and 50% of the liver cytochrome P-450 in acrolein-treated microsomes did not support the N-demethylation of benzphetamine or ethylmorphine or hydroxylation of aniline because of the total loss of NADPH-cytochrome c reductase. Addition of purified NADPH-cytochrome c reductase to the acrolein-treated lung or liver microsomal suspension largely restored these monooxygenase activities. Addition of glutathione or dithiothreitol to the lung or liver microsomal suspension prior to the addition of acrolein significantly protected cytochrome P-450 from conversion to cytochrome P-420 as well as NADPH-cytochrome c reductase from inactivation. Thus, selective conjugation of acrolein with lung and liver NADPH-cytochrome c reductase but not cytochrome P-450 was responsible for total loss of these lung and liver monooxygenase activities.