Ischemia refers to the condition of no blood flow. When the artery perfusing an

Question

Ischemia refers to the condition of no blood flow. When the artery perfusing an area of tissue is blocked, oxygen can no longer be delivered to support energy metabolism. Under these conditions, the ATP concentration falls and ADP and Pi concentrations rise. What will this do to the free energy of ATP hydrolysis (also called the affinity of ATP hydrolysis)? What do you think will be the consequence of ischemia on the effectiveness of the ion pumps? (Kammermeir, Schmidt, and Jungling, Free energy change of ATP hydrolysis: a causal factor of early hypoxic failure of the myocardium? J. Mol. Cell Cardiol. 14:267-277, 1982).

Explanation / Answer

there will be a 5% reduction in the free energy of atp hydrolysis in the reduction of ATP in the cell. Since it is a hydrolysis reaction, the ADP and Pi will come together to form ATP which will then be hydrolyzed to give energy.

The ion pumps which are dependent on ATP will fail, including calcium pumps. The substrates will accumulate in the cell. High levels of calcium increases the level of glutamate. Glutamate induces more entry of calcium into the cell. This causes the production of free radicals and reactive oxygen species. Phospholipases are activated by the high levels of calcium.

Since phospholipids make up the cell membrane, this will result in the apoptosis of the cell.

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