Increases in cytosolic calcium are a primary factor that destroys mitochondria.
Mitochondria, the powerhouses of the cell, are vulnerable to various injurious stimuli. These stimuli ultimately disrupt their function and can lead to their destruction. While a variety of factors contribute, increases in cytosolic calcium are particularly damaging.
Injurious Stimuli Targeting Mitochondria
Mitochondria are targeted by a range of harmful substances, including:
- Oxidants: These molecules cause oxidative stress, damaging mitochondrial components.
- Electrophiles: These substances react with and modify mitochondrial proteins.
- Lipophilic Cations: These positively charged molecules accumulate within the mitochondria, disrupting its function.
- Weak Acids: These compounds can alter the pH within the mitochondria, interfering with its processes.
- Hypoxia: Oxygen deprivation leads to energy depletion and mitochondrial dysfunction.
- Toxins: Various toxins directly impair mitochondrial processes.
The Role of Calcium
Increased cytosolic calcium is a critical trigger for mitochondrial damage. Excess calcium inside the mitochondria can:
- Disrupt the mitochondrial membrane potential: leading to swelling and eventual rupture.
- Activate enzymes: Like phospholipases, leading to the degradation of mitochondrial membranes.
- Induce the mitochondrial permeability transition (MPT): A sudden increase in the permeability of the inner mitochondrial membrane, leading to mitochondrial swelling, uncoupling of oxidative phosphorylation, and ultimately, cell death.
In summary, while many factors can damage mitochondria, a surge in cytosolic calcium levels is a key element that significantly contributes to their destruction.
