Fig. 2. Full kinetic response of the proton leak rate to changes in membrane potential of liver and skeletal muscle mitochondria of fed WA cane toads. Liver mitochondria have a lower basal proton leak than skeletal muscle mitochondria. A rough extrapolation of the skeletal muscle and the liver curve would suggest that the lower liver proton leak is achieved by a decrease in the respiratory chain activity and not via a change in the proton leak kinetic function. Values are means ± s.e.m., N=9.