Effects of octanoate on rat brain and liver mitochondria

Octanoate increased state 3 and state 4 respiration in rat liver mitochondria. The respiratory control rates decreased because state 4 was disproportionately affected. The ADP:0 ratio was not affected. Octanoate produced a fall in the protonmotive force (∆p) of 30 mV during state 3 and state 4. The mitochondrial inner membrane proton conductance (C_{m, h}⁺) increased twofold during state 4. Similar effects were observed in polarographic assays of brain mitochondria, but measurements of ∆p and C_{m, H}⁺ were not possible. Octanoate produces loose coupling in isolated mitochondria. This effect may play a role in the pathogenesis of Reye’s syndrome.