Respiratory burst is the rapid release of reactive oxygen species (superoxide radical and hydrogen peroxide) from different types of cells.
Usually it denotes the release of these chemicals from immune cells, e.g. neutrophils and macrophages, as they come into contact with different bacteria or fungi. They are also released from the ovum of higher animals after it has been fertilized. These substances can also be released from plant cells.
NADPH oxidase leads to superoxide anion production. The superoxide reacts with NO resulting in the formation of peroxynitrite, reducing the bioactive NO needed to dilate terminal arterioles, feed arteries and resistance arteries. Superoxide anion, peroxynitrite and other reactive oxygen species also lead to pathology via peroxidation of proteins and lipids and via activation of redox sensitive signalling cascades and protein nitrosylation.
Respiratory burst plays an important role in the immune system. It is a crucial reaction that occurs in phagocytes to degrade internalized particles and bacteria.
NADPH oxidase, an enzyme family in the vasculature (particularly in vascular disease) produces superoxide, which spontaneously recombines with other molecules to produce reactive free radicals. NADPH oxidase activation has been suggested to depend on prior PKC activation. Myeloperoxidase uses one of these free radicals, hydrogen peroxide, to produce hypochlorous acid. Many vascular stimuli, including all those known to lead to insulin resistance, activate NADPH oxidase via both increased gene expression and complex activation mechanisms.
Respiratory burst is sometimes called oxidative burst.