Respiratory control in cockroach-muscle mitochondria

Mitochondria isolated from cockroach thoracic muscles have been used to demonstrate that the rate of oxidation of several Krebs-cycle intermediates is under the control of adenosine diphosphate concentration. Respiratory-control indices as high as 25 have been achieved with both pyruvate and glutamate. Contrarily, the rate of oxidation of α-glycerol phosphate is influenced by adenosine diphosphate concentration to only a minor degree, but is markedly inhibited by accumulation of the oxidation product. When the ratio [reactant]/[product] is approx. 3, oxidation of α-glycerol phosphate becomes very low. These findings are used to propose a theory which may satisfactorily explain the problem of respiratory control in insect muscles.