Electroorientation effect of isolated mitochondria in different functional states

For the first time, the electroorientation effect of isolated rat liver mitochondria has been investigated in a nonuniform alternating electric field at frequencies from 50 to 10(7) Hz. Two relaxation regions of mitochondria electroorientation have been revealed; they are due to the presence of low-frequency alpha - and high-frequency beta-dispersion. It has been shown that incubation of mitochondria in a medium with a low electroconductivity as well as in the presence of ionophores (valinomycin, 2,4-dinitrophenol) results in a decreased electroorientation value in the region of the high-frequency structural polarization. This is explained by a marked lowering of the effective electroconductivity of mitochondria due to changes in the permeability of the inner membrane of organelles. Upon the addition of ionophores, the decrease in the electroorientation effect value becomes more pronounced. Inhibition of respiration of mitochondria by antimycin A resulted in a slight diminution of the effect, followed by time-dependent stabilization, probably due to a lowered electroconductivity of the mitochondrial matrix, induced by the reduction of pH in the intramitochondrial space, change in the ionization of inner enzyme structures, and a partial limitation of the inner ion mobility.