Abstract
Mitochondria require oxygen to produce ATP in sufficient quantities to drive energy-requiring reactions in eukaryotic organisms. The measurement of oxygen consumption rates from isolated mitochondria in vitro is a useful and valuable technique in the research and evaluation of mitochondrial dysfunction and disease since ADP-dependent oxygen consumption directly reflects coupled respiration or oxidative phosphorylation (OXPHOS). This chapter describes the traditional method of mitochondrial polarography using a Clark electrode for measuring coupled respiration in freshly isolated mitochondria from both mammalian tissues and Drosophila melanogaster.