RESUMEN
In experiments on isolated kidney and liver mitochondria, it is shown that oleate hydroperoxide induces a much smaller increase in the controlled respiration rate and DeltaPsi decrease than the same concentrations of oleate. Palmitate appears to be less efficient than oleate but more efficient than oleate hydroperoxide. In all cases, GDP and CAtr cause some recoupling, CAtr being more effective. Addition of 0.2 mM GDP before CAtr does not prevent further DeltaPsi increase by subsequent CAtr addition. On the other hand, GDP added after CAtr is without any effect. GDP partially prevents the DeltaPsi lowering by ADP at the State 4--State 3 transition if small amounts of CAtr are present. The data are consistent with the suggestion of F. Goglia and V.P. Skulachev (FASEB J. 17, 1585-1591, 2003) that fatty acid anions are translocated by mitochondrial anion carriers much better than their hydroperoxides. As to GDP recoupling, it cannot be regarded as a specific probe for uncoupling by UCPs since it can be mediated by the ATP/ADP antiporter.