Chemical-induced modulation of ATP and protein synthesis processed inside rat brain mitochondria.

Rates of ATP production and protein synthesis rates were simultaneously studied using the isolated rat brain mitochondria and different types of brain polysomes (total, free, microsomal and mitochondrial membrane-bound). Protein synthesis was measured using a special reticulocyte lysate cell-free incubation medium. Prior to incubation, the intact ("unbroken") mitochondria were pretreated by several xenobiotics and natural metabolic effectors. The mitochondria incubated without these additions were used as controls. Chemically-promoted inhibition of ATP systhesis correlated with a significant activation of protein synthesis directed by the mitochondrial membrane-bound polysomes. The induction of ATP synthesis leads to a marked suppression of mitochondrial translation. Application of the selective translation blockers do not influence the ATP formation inside the isolated mitochondria. In general, mitochondrial membrane-found polysomes isolated from the intact normal organella are least active as compared with other tested polysomal fractions while the releasing of polysomes from mitochondrial membranes by Triton X-100 leads to the essential increase of the activity of these separated translation mechanisms. The separation of polysomes from the microsomal membranes do not change the activity of the former. A possible molecular mechanism, interdependence and biological significance of the established phenomena are discussed.