Uncoupling by Sodium Alkyl Sulfates of Energy-Linked Functions of Rat Liver Mitochondria

Summary

Sodium octyl, decyl, dodecyl, and tetradecyl sulfates were tested for uncoupling activity against energy-linked functions of rat liver mitochondria. All four detergents diminished respiratory control with either succinate or L-glutamate as substrate. The alkyl sulfates augmented mitochondrial swelling and, at high concentrations, the detergent depressed energized (ATP) contraction. The latter incompetency may be partially due to lysis of the organelle by the detergent.

The potency of the detergents for both depression of respiratory control and inhibition of energized recovery from swelling by 40% [log(l/I ₄₀) and log (l/R ₄₀), respectively] was a function of the number of methylene groups in the alkyl sulfate. This potency was equated with the lipophilicity of the molecules as measured by their partitioning across the interfacial barrier of n-octanol and water. Uncoupling and inhibition of recovery from swelling required lesser amounts of a molecule that was lipophilic than one that was hydrophilic.