An Introduction to Reactive Oxygen Species – Measurement of ROS in Cells

Mye interessant om ROS (reactive oxygen species), som er skadevirkningene fra oksygenforbruk. Nevner ikke CO2 som antioksidant, men beskriver superoksid dismutase, glutathion og c-vitamin, m.m. Glutathion er viktigste intra-cellulære antioksidant.

Reactive Oxygen Species (ROS) have long been known to be a component of the killing response of immune cells to microbial invasion. Recent evidence has shown that ROS play a key role as a messenger in normal cell signal transduction and cell cycling.

Reactive Oxygen Species (ROS) is a phrase used to describe a number of reactive molecules and free radicals derived from molecular oxygen. The production of oxygen based radicals is the bane to all aerobic species.

Detoxification of reactive oxygen species is paramount to the survival of all aerobic life forms. As such a number of defense mechanisms have evolved to meet this need and provide a balance between production and removal of ROS. An imbalance toward the pro-oxidative state is often referred to as “Oxidative stress”.

The effect of reactive oxygen species on cellular processes is a function of the strength and duration of exposure, as well as the context of the exposure. The typical cellular response to stress is to leave the cell cycle and enter into G0. With continued exposure and/or high levels of ROS, apoptosis mechanisms are triggered.

Reactive oxygen species have a role in a number of cellular processes. High levels of ROS, which can lead to cellular damage, oxidative stress and DNA damage, can elicit either cell survival or apoptosis mechanisms depending on severity and duration of exposure.

The interest in reactive oxygen species originally revolved around the pathology associated with the deleterious effects of aerobic respiration: the necessary evil caused by the leakage from the electron transport chain in mitochondria. In this context, research involved the role that these agents played in aging, chronic diseases and cancer.

A new frontier was born with the discovery that the “oxidative burst” by phagocytic cells was actually the result of the intentional production of reactive oxygen species. This was thought to be a very specific application where specific cells produced what can only be described as toxic agents in order to kill invading microorganisms. Further recent work has shown that ROS are produced in all cell types and serve as important cellular messengers for both intra- and inter-cellular communications. It is now apparent that a very complex intra-cellular regulatory system involving ROS exists within cells. Cells respond to ROS moieties in different ways depending on the intensity, duration and context of the signaling. In regards to intracellular signaling it appears that hydrogen peroxide (H2O2) is the most interesting candidate, while nitric oxide (•NO) is involved primarily with intercellular signaling.

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