[Mechanism of opiate of oxidative phosphorylation in mitochondria]

Effect of morphine, codeine, dionine and nalorphine on the oxidative phosphorylation in rat liver mitochondria was studied. Morphine is found to inhibit both ATP-synthetase and ATP-ase activities in mitochondria, but not in submitochondrial particles. Morphine-suppressed oxidative phosphorylation was competitively reversed with high concentrations of ADP, but not of inorganic phosphate. The effect of other opiates (i.e. codeine, dionine, nalorphine) was similar. It is suggested, that opiates inhibit the transport of adenine nucleotides through inner mitochondrial membrane, as it does atractyloside. A significance of the hydrophobic interaction between the inhibitor and adenine nucleotide translocase is outlined, since the degree of the inhibition of oxidative phosphorylation is increased with the increase in the number of non-ionized opiate molecules (at alkaline pH values) and in the length of the carbon chain of narcotic molecule as follows: morphine--codeine--dionine--nalorphine.