Homeostasis of the protonmotive force in phosphorylating mitochondria.
The relationship between the respiration rate and the magnitude of the electrochemical proton potential (delta mu H+) in rat liver mitochondria was investigated. (1) Under the active-state conditions, the action of inhibitors of either phosphorylation (oligomycin) or respiration (rotenone, malonate) on the respiration and delta mu H+ was measured. Both inhibitors diminished the respiration, whereas rotenone resulted in a decrease of delta mu H+, and oligomycin produced an increase of this potential. The effect of the inhibitors was much more pronounced on the respiration rate than on delta mu H+; for example, the excess of oligomycin produced a 90% inhibition of the respiration while delta mu H+ was changed only by 9%. (2) Under the resting-state conditions, small concentrations of the uncoupler stimulated the respiration while changing delta mu H+ to a relatively small extent. The uncoupler concentrations which doubled and tripled the respiration rate produced only 5 and 9% decrease of delta mu H+, respectively. (3) The present results enabled us to propose a model describing the interrelationship between respiration and delta mu H+.
D000818:Animals; D006706:Homeostasis; D008314:Malonates / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000502:physiology*; D009840:Oligomycins / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D010766:Phosphorylation; D011522:Protons; D051381:Rats; D012402:Rotenone / Q000494:pharmacology
D008314:Malonates; D009840:Oligomycins; D011522:Protons; D012402:Rotenone; C030290:malonic acid