Reversible Organization of Mitochondria into Associates as a Factor Regulating Respiration

M. N. Kondrashova,^1,2 T. V. Sirota,¹ A. V. Temnov,¹ Zh. V. Belousova,¹ and V. V. Petrunyaka¹

¹Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; E-mail: kondrashova@venus.iteb.serpukhov.su

²To whom correspondence should be addressed.

Submitted September 20, 1996; revision submitted October 23, 1996.

Mitochondria in the form of associates close to their state in the quiescent cell were obtained in rat liver homogenate under physiological for cytosol concentrations of potassium and calcium ions and small dilution of tissue. Associates in such homogenates are stable on storage in ice for several hours. Dissociation of associates is induced by dilution of the homogenate, addition of EDTA, or by administration of adrenalin to the animal. Respiration rate is increased and ADP/O ratio is decreased when associates dissociate. The observed increase in respiratory rate induced by adrenalin administration in vivo is decreased or abolished when associates are dissociated in the incubation medium induced by influences in vitro. This is due to hyperactivation of respiration which leads to inhibition of succinate oxidation by oxalacetate. Under the conditions preserving the associates of mitochondria a close interaction of oxidative and transamination processes is observed as well as a broader range of metabolic states of mitochondria than in standard preparations which dissipate into single granules on isolation in sucrose, high dilution, and washing.

KEY WORDS: mitochondria, respiration regulation, adrenalin effect, transamination, associates in cells.

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