Mitochondrial effect of orally administered dibutyl phthalate in rats.

activity in liver homogenate from di-2-ethylhexyl phthalate (DEHP)-treated rats. Ohyama9) showed in vitro that PAEs inhibited mitochondrial respiration, with di-n-butyl phthalte (DBP) showing the strongest effect, and he concluded that PAEs were inhibitors of electron and energy transfer systems but not uncouplers. Takahashi10) also found inhibitory effects of PAEs on respiration in vitro and ascertained that PAEs acted mainly as energy-transfer inhibitors. Then, Inouye et al.11) reported that PAEs acted in vitro as uncouplers rather than electron-transfer inhibitors. Thus, these reports did not always coincide in terms of the site of action of PAEs on the mitochondrial respiration. In order to determine the inhibitory site of PAEs in mitochondrial respiration, we studied the effects of DBP on respiratory activity and dehydrogenases activities in rat liver mitochondria in vivo and in vitro.