Body size is a central biological parameter affecting most biological processes (especially energetics) and the mitochondrion is a key organelle controlling metabolism and is also the cell's main source of chemical energy. However, the link between body size and mitochondrial function is still unclear, especially in ectotherms. In this study, we investigated several parameters of mitochondrial ...

Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each...

Kurochkin IO, Etzkorn M, Buchwalter D, Leamy L, Sokolova IM. Top-down control analysis of the cadmium effects on molluscan mitochondria and the mechanisms of cadmiuminduced mitochondrial dysfunction. Am J Physiol Regul Integr Comp Physiol 300: R21–R31, 2011. First published September 15, 2010; doi:10.1152/ajpregu.00279.2010.—Cadmium (Cd) is a toxic metal and an important environmental pollutant...

Mitochondrial proton leak is the largest single contributor to the standard metabolic rate (SMR) of a rat, accounting for about 20% of SMR. Yet the mechanisms by which proton leak occurs are incompletely understood. The available evidence suggests that both phospholipids and proteins in the mitochondrial inner membrane are important determinants of proton conductance. The uncoupling protein 1 h...

Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be attributed to mitochondrial anion carriers, w...

To investigate the role mitochondrial membrane lipids play in the actions of CR (calorie restriction), C57BL/6 mice were assigned to four groups (control and three 40% CR groups) and the CR groups were fed diets containing soya bean oil (also in the control diet), fish oil or lard. The fatty acid composition of the major mitochondrial phospholipid classes, proton leak and H(2)O(2) production we...

Cytochrome cbb(3) belongs to the superfamily of respiratory heme-copper oxidases that couple the reduction of molecular oxygen to proton translocation across the bacterial or mitochondrial membrane. The cbb(3)-type enzymes are found only in bacteria, and are both structurally and functionally the most distant from their mitochondrial counterparts. The mechanistic H(+)/e(-) stoichiometry of prot...

Proton pumping across the mitochondrial inner membrane and proton leak back through the natural proton conductance pathway make up a futile cycle that dissipates redox energy. We measured respiration and average mitochondrial membrane potential in perfused rat hindquarter with maximal tetanic contraction of the left gastrocnemius-soleus-plantaris muscle group, and we estimate that the mitochond...