INFLUENCE OF THE ANESTHETIC 2,6-DIISOPROPYLPHENOL ON THE OXIDATIVE-PHOSPHORYLATION OF ISOLATED RAT-LIVER MITOCHONDRIA

Isolated rat liver mitochondria have been incubated in the presence of the general anesthetic 2,6-diisopropylphenol (0-100-mu-M) and the efficiency of oxidative phosphorylation has been evaluated by measuring the respiratory rates, the rates of ATP synthesis or hydrolysis and the magnitude of the transmembrane electrical potential. The results obtained indicate that: (a) in mitochondria energized either by succinate or by ATP, 2,6-diisopropylphenol decreased the transmembrane electrical potential and increased the rates of either electron transfer or ATP hydrolysis; (b) in succinate-energized mitochondria 2,6-diisopropylphenol, at concentrations causing substantial depression of the transmembrane electrical potential, did not modify either the rate of phosphorylation of added ADP or the rate of ADP-stimulated respiration; (c) in succinate-energized mitochondria 2,6-diisopropylphenol caused a concentration-dependent inhibition of the uncoupler-stimulated rate of succinate oxidation. These findings suggest that under the experimental conditions reported 2,6-diisopropylphenol affected the generation and/or maintenance of the transmembrane electrical potential while leaving unchanged the coupling between the electron flow in the respiratory chain and the synthesis of ATP.