The impairment of mitochondrial function by Triton X-100. A study of mitochondrial respiration and energy-dependent swelling.

Coupled and uncoupled respiration, and energy-dependent phosphate swelling have been studied in rat liver mitochondria in the presence of various concentration of Triton X-100. Detergent concentrations up to 10(-5) M do not affect any of the processes under study. At 10(-5) M, Triton X-100 produces a slight decrease of coupled respiration and a considerable inhibition of mersalyl-induced shrinking in swollen mitochondria. Increasing the surfactant concentration to 10(-4), coupled as well as uncoupled O2 consumption is decreased, succinate-dependent phosphate swelling is inhibited and an energy-dependent phosphate swelling in the absence of valinomycin is observed. At 2 X 10(-4) M. Triton X-100, ATP- dependent phosphate swelling is abolished, and passive swelling may be induced by various ions. Higher detergent concentrations do not allow observation of any of these events. On the basis of these results, a model of membrane-detergent interaction is proposed.