4-Hydroxy-2-nonenal (HNE), an aldehyde end product of lipid peroxidation in biological systems, is capable of producing a range of powerful biological effects. Despite its biological relevance, the metabolic fate of this aldehyde is unknown in vivo. This study examines the urinary excretion of HNE in the rat and the nature of metabolites formed. Following iv administration of L3H1HNE, the majority of the dose appeared in urine (67.1% after 48 h). ...