Mechanism of cell death in a myocardial infarction

In a myocardial infarction blood supply to a certain area of the heart muscle is cut off. Most often this happens due to an obstruction of a coronary artery.As the heart muscle cells are very active they have a high oxygen demand. Since o2 supply is cut off these cells enter a hypoxic state. Hypoxia affects oxidative phosphorylation in mitochondria and this causes the available ATP levels in the cell to decline. With the decrease of ATP, cellular AMP level increases. This increases AMP: ATP ratio and stimulates Phospho fructo kinase (PFK-1) enzyme. This enhances the rate of anaerobic glycolysis.

With the increased rate of anaerobic glycolysis,

1. Depletion of glycogen stores
2. Increase in intracellular lactic acid levels occur.

This increases intracellular acidity (decrease in pH)

Falling of the intracellular pH destabilizes the lysosomal membrane and causes hydrolytic enzymes in the lysosomes to come out. These enzymes hydrolyze intracellular biological molecules and ultimately lead to cell death. Ribosomes dissociate from RER and polysomes also dissociate.

In the other hand decreased ATP levels in the cell affect the function of Na+/K+ ATPase pump and causes Na+ to accumulate within the cell. This causes mitochondria, ER and the entire cell to swell. Blebs also appear on the cell surface.