Search

The paper deals with the effect of fasting on the content and transport of potassium ions in the rat liver mitochondria as well as on oxidative phosphorylation. It is shown that the concentration of potassium ions in the mitochondria under fasting lowers by 20-30% at an average as compared to the control. The rate of potassium ions release from the mitochondria in the presence of DNP also lowers. It is found that the respiratory control ratio after 24-h fasting decreases and increases after 48-h fasting. Possible reasons of changes in the transport of potassium ions in the rat liver mitochondria in fasting are discussed.

The content of potassium ions in rat liver mitochondria after intensive physical work (continuous swimming) is increased approximately 2-fold, while the rate of K+ efflux from the mitochondria is significantly reduced. A considerable increase of the "calcium capacity" and a decrease of the respiration rate in state 4 were found. The experimental results indicate that during intensive physical work the mitochondrial membrane resistance to the damaging effects is enhanced. A possible mechanism of these changes is discussed.

Transport of Pi into mitochondrial matrix induces K+-permeability of the membranes, which results from the addition of DNP. This induction of K+ efflux is eliminated by some agents causing the respiratory chain reduction (e.g. succinate, rotenone, antimycin A). It was shown that the abolition of the membrane potential is not sufficient for K+ efflux induction. The latter process is necessary for the energy-linked formation of the K+-transporting system. The lipid fraction containing lecithin and monophosphoinositol was extracted from the mitochondria after preincubation with Pi. The artificial bilayer membranes formed from these lipids are permeable for K+.