EFFECT OF HYDROPHOBIC ORGANIC-COMPLEX OF CADMIUM ON ION PERMEABILITY OF MITOCHONDRIAL-MEMBRANE AND ON RESPIRATION OF RAT-LIVER MITOCHONDRIA

The effect of a hydrophobic complex of CdCl2 and 1,3-bis(4-chlorbenzil idenamino) guanidine on the respiration of rat liver mitochondria was studied in vitro. Similarly to Cd2+, the complex reduced the effective ness of the oxidative phosphorylation and mitochondrial respiration in the state 4 and in the presence of DNP. The toxicity of the complex w as higher then that of Cd2+. Under the same experimental conditions, t he ligand produced no effect on the mitochondrial respiration in the p resence of DNP. The toxic effect of the complex on the mitochondrial r espiration was higher than the summary action of us components. High a ctivity of the complex was suggested to be due to its hydrophobicity b ecause the enzyme active SH-groups are located in hydrophobic domains of the mitochondrial membrane. In experiments on the transmembrane dis tribution of Cs-137 and Rb-86 in succinate-energized mitochondria at 2 0 degrees C, the susceptibility of the toxic effects caused by the com plex was lower than that, caused by Cd2- in presence of ruthenium red a blocker of Ca2+ transport. These agents were assumed to be transport ed in mitochondria via different pathways. The experiments on mitochon drial swelling in a medium containing 125 nM KNO2 or NH4NO3 revealed t hat the complex displayed stronger protonophoric effect in comparison with that caused by the ligand. The ligand selectively increased the p roton permeability of the mitochondrial membrane and produced no effec t on the K+-permeability of the membrane. This fact correlated well wi th the activation effect of the complex and Cd2+ on the respiration of mitochondria (state 4).