Conventional techniques to monitor mitochondrial oxygen consumption.

Following several key discoveries on hypoxia-inducible factors, we have observed an explosion of studies investigating how the hypoxic microenvironment provokes bioenergetic alterations. This is particularly relevant for cancer cells, as they are often exposed to hypoxic conditions in the course of tumor progression. Thus, interest in the measurement of oxygen consumption at the tissue, cell, or mitochondrion level has been revived. Here, we describe the basic principles of cellular respiration and survey some of the conventional methods for measuring O2 consumption in intact or permeabilized cells.