Preservation of native properties of mitochondria in rat liver homogenate.

A protocol is developed for preparation of concentrated rat liver homogenate preserving assemblies of mitochondria in isotonic KCl under 0 and 15 degrees C. Assemblies preserve ability for self-organization during storage in homogenate. All key energy functions of mitochondria can be investigated in such a homogenate. Oxidative phosphorylation and membrane potential are stable for 5-7 h and can be still observed on the next day. Substrate-level phosphorylation is better pronounced for mitochondria in KCl than in sucrose medium while Ca2+ capacity is greater and lipid peroxidation is much lower. Sucrose addition impairs these functions. The rate of phosphorylating respiration is lower in large assemblies and higher in small. Transition from large to small assemblies corresponds to the transition from quiescent state of animal to adrenaline induced active state. The proposed method is particularly convenient for clinical investigations with small bioptates.