[Mitochondria from rat brain purified by partition in biphases].

Rat brain mitochondria and synaptosomes can be separated by partition in polyethileneglycol-Dextran biphases. Mitochondria obtained by this method show very low contamination with synaptosomes and good respiratory activity. Their respiratory activity may be stimulated by exogenous potassium when they are obtained in potassium depleted media. These mitochondria show the highest purity described till now, in terms of the lactate dehydrogenase and acetylcholinesterase activities found in their preparations.