REVERSIBLE ORGANIZATION OF MITOCHONDRIA INTO ASSOCIATIONS AS A FACTORREGULATING RESPIRATION

Mitochondria in the form of associations close to their state in the q uiescent cell were obtained in rat liver homogenate under physiologica l for cytosol concentrations of potassium and calcium ions and small d ilution of tissue. Associations in such homogenates are stable on stor age in ice for several hours. Dissociation of associations is induced by dilution of the homogenate, addition of EDTA, or by administration of adrenaline to the animal. Respiration rate is increased and ADP/O r atio is decreased when associations dissociate. The observed increase in respiratory rate induced by adrenaline administration in vivo is de creased or abolished when associations are dissociated in the incubati on medium induced by influences in vitro. This is due to hyperactivati on of respiration which leads to inhibition of succinate oxidation by oxaloacetate. Under the conditions preserving the associations of mito chondria a close interaction of oxidative and transamination processes is observed as well as a broader range of metabolic states of mitocho ndria than in standard preparations which dissipate into single granul es on isolation in sucrose, high dilution, and washing.