Aerobic metabolism depends on oxygen and is a hallmark of mammalian cells where this is the primary mechanism of energy production. The process takes place in the mitochondria. Aerobic respiration is, however, a most dangerous activity, inevitably generating significant amounts of free radicals, which, if unregulated, can cause extensive damage within cells, targeting such structures as membranes and DNA. Such damage is seen in reperfusion injury following stroke and ischemia.  Life- long, oxidative, free radical damage to mitochondrial DNA may also contribute to female infertility and neural degenerative diseases.  Metabolic processes, located in the glycolytic pathway and Krebs cycle, can also play regulatory roles in cell function as is proposed for the secretion of insulin from pancreatic beta-cells.  Other health issues related to metabolism include the, now all to prevalent, occurrence of obesity and diabetes.

Understanding the role of mitochondria in both health and disease has been constrained by the lack of good techniques for examining a single cell and the dynamics of their performance. Core research at the BRC has specifically targeted this area of interest, developing both new single cell electrochemical and imaging approaches. Additionally, installation of extant technologies, such as confocal microscopy and membrane potential dyes, has produced powerful and unique integrated experimental platforms.

The electrochemical technique of self-referencing either ion selective or amperometric electrodes has proved particularly useful in studying metabolism. The micron sized non-invasive oxygen electrode produced the first recordings of single cell oxygen consumption and has since been used to monitor several metabolic events and processes (Land, 1997). The same is true of the more recently developed enzyme assisted glucose electrode (MacLellan, 2005). Currently, in response to our user base, we are developing a lactate probe to help examine anaerobic or hypoxic conditions.

One product of oxygen consumption through the electron transfer chain and the mitochondrial inner membrane F1F0 ATP synthase is ATP and a change in the ADP/ATP ratio. ATP can thus not only form a critical source of energy via the phosphate bond, but can also act as a signaling molecule for metabolic state. ATP can be directly measured via a luminescent reaction. The luciferin/luciferase reaction, in the presence of ATP, generates photons. Thus, photon density relates to ATP concentration.   The BRC is developing new sensitive photon counting and imaging devices to follow this reaction at the single cell or population level. A luciferase adenovirus is available for incorporating the viral genome sequence into the target cell. Luciferase was originally isolated from the Fire Fly.