[Effect of valinomycin and nonactin on monovalent cation transport in mitochondria].

Unidirectional fluxes of tracers 137Cs+ (+valinomycin) and 204Tl+ (+nonactin) in mitochondria maintained under stationary state at 0 degree C have been studied. The tracer uptake in energized mitochondria (Q infinity Cmit/Cmed = Kin/kout) was about 10 times as high compared to that in a deenergized state. Energization caused a 5-10 fold increases of the influx rate constant kin, while the efflux rate constant, kout, decreased only by 1.5-2 times of less. There was a positive correlation between Q infinity and kin. No correlation could be found between Q infinity and kout. The results obtained suggest that under the experimental conditions studied the energization did not increase substantially the membrane potential expected to retard the efflux of permeant cations. In the presence of ionophores the monovalent cations are supposed to be accumulated in mitochondria against the electrochemical gradient.