Enzymic Catalysis of the Accumulation of Acetaldehyde From Ethanol in Human Prenatal Cephalic Tissues: Evaluation of the Relative Contributions of CYP2E1, Alcohol Dehydrogenase, and Catalase/Peroxidases

作者：Richard Person, Hao Chen, Alan G. Fantel, Mont R. Juchau · 发表于：Alcoholism Clinical and Experimental Research · 年份：2000 · DOI：10.1111/j.1530-0277.2000.tb02114.x · 被引用次数：32 · 研究领域：Prenatal Substance Exposure Effects、Alcohol Consumption and Health Effects、Poisoning and overdose treatments

BACKGROUND: The human prenatal brain is very sensitive to the toxic effects of ethanol, but very little information is available concerning the conversion of ethanol to the highly cytotoxic metabolite, acetaldehyde, in that organ. Thus, experiments were designed to investigate rates of accumulation of acetaldehyde from ethanol in the prenatal human brain. METHODS: Prenatal human cephalic tissue homogenates were used as enzyme sources and were compared with analogous preparations of adult rat livers. Generated acetaldehyde was derivatized with cyclohexane-1,3-dione to yield fluorescent decahydroacrizine-1,8-dione, which was readily separated, detected, and quantitated with HPLC. RESULTS: Detected rates of accumulation were unexpectedly high, even in the absence of added NADPH, NAD+, or H2O2, which are cofactors/cosubstrates for cytochrome P-450-, alcohol dehydrogenase- and catalase/peroxidase-catalyzed reactions, respectively. Without added cofactors/cosubstrates or other components and under linear reaction conditions, rates in human prenatal cephalic preparations were approximately 20% of those observed with analogous preparations of adult rat livers. Cofactor/cosubstrate-independent reactions were localized in the cytosolic (soluble) fraction and were strongly dependent on molecular oxygen (O2). They were not inhibited substantially by carbon monoxide (CO:O2 = 80:20 vs N2:O2 = 80:20) or by pyrazole in concentrations up to 10 mM and were only weakly inhibited by azide. Prein...