GLUCOSE STIMULATES RESPIRATION OF LIVER-MITOCHONDRIA UNDER CONDITIONSOF HEXOKINASE INACTIVATION - EFFECTS OF SUCROSE AND INHIBITORS OF OXIDATIVE-PHOSPHORYLATION

Effects of glucose on the respiration of liver mitochondria have been studied under conditions excluding its phosphorylation by the mitochon drial hexokinase. Glucose was shown to stimulate state 3 respiration i n mitochondria if they were isolated without washing or incubated with KCl. The rates of both state 4 respiration and respiration in the pre sence of the uncoupling agent 2,4-dinitrophenol were unaffected. The c oncentration of glucose sufficient to effect half-maximal stimulation was 2.4 mM. This effect was precluded by washing the mitochondria in t he presence of KCl or isolating them in sucrose-containing media. The inhibition of the glucose-induced effect by sucrose was competitive. O ligomycin eliminated the stimulating effect of glucose at concentratio ns decreasing the rate of state 3 respiration by 20%. Under similar co nditions carboxyatractyloside acted as a potent co-stimulator. It is c oncluded that glucose can regulate oxidative phosphorylation by affect ing the adenine nucleotides transporter.