The possible role of palmitoyl-CoA in the regulation of the adenine nucleotides transport in mitochondria under different metabolic states. I. Comparison of liver mitochondria from starved and fed rats.

It has been shown that KM values for ADP when rat liver mitochondria oxidized succinate were strictly dependent on the values of the respiratory control ratios. The Ki values for palmitoyl-CoA inhibition of the ADP-stimulated succinate oxidation and the inhibition of the uncoupler-stimulated ATPase activity were equal to 0.5 muM. Mitochondria from livers of starved rats showed 30% inhibition of the state 3 respiratory rate (compared to the uncoupled respiratory rate) which was abolished by addition of carnitine. It was supposed that this inhibition was due to the influence of acyl-CoAs bound to the inner mitochondrial membrane on the adeninenucleotide translocase. Mitochondria from livers of fed rats showed a strong inhibition of succinate oxidation both in state 4 and state 3, although the rate of uncoupled respiration was normal. It was assumed that in this case the changes in mitochondrial behaviour was caused by the decrease in the concentration of ADP and ATP in the matrix space of mitochondria.