Under hypoxic conditions, the mitochondrial respiratory chain also produces nitric oxide (NO), which can generate reactive nitrogen species (RNS). RNS can further generate other reactive species, e.g., reactive aldehydes-malondialdehyde and 4-hydroxynonenal, by inducing excessive lipid peroxidation.
Biology · High School · Sun Jan 24 2021
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- Under normal conditions, the mitochondrial respiratory chain is involved in energy production by using oxygen to generate ATP (adenosine triphosphate), the cellular "energy currency." However, under hypoxic conditions (low oxygen levels), the efficiency of this process decreases, leading to the incomplete reduction of oxygen. This incomplete reduction can lead to the production of nitric oxide (NO) in the mitochondria.
- Nitric oxide is a signaling molecule with various functions within the body, including vasodilation and neurotransmission. But when produced in excess, particularly under oxidative stress or hypoxic conditions, NO can react with other molecules to form reactive nitrogen species (RNS).
- RNS, similar to reactive oxygen species (ROS), can be damaging to cells. They can modify proteins, DNA, and lipids, potentially leading to cell dysfunction or death. One of the pathways through which RNS exert damage is through lipid peroxidation, a process in which free radicals attack lipids containing carbon-carbon double bond(s), particularly in cell membranes.
- Lipid peroxidation results in the formation of reactive aldehydes such as malondialdehyde (MDA) and 4-hydroxynonenal (HNE). These aldehydes can further react with cellular components, causing additional damage and contributing to the pathophysiology of various diseases.