Which area of the kidney is most susceptible to anoxic injury during oxygen deprivation?

• A. Bowman capsule
• B. Distal convoluted tubule
• C. Proximal tubule
• D. Efferent arteriole

Answer: (C)

The proximal tubule is the area of the kidney most susceptible to anoxic injury during oxygen deprivation. This susceptibility can be attributed to several factors.

Firstly, the proximal tubule is highly metabolically active; it is responsible for the reabsorption of a significant amount of filtered water, sodium, bicarbonate, glucose, and other solutes. This high metabolic activity leads to a greater demand for oxygen, making these cells particularly vulnerable in situations where there is reduced oxygen availability.

Moreover, the proximal tubule has a dense network of mitochondria to support its energy needs, and when oxygen levels drop, the inability to carry out oxidative phosphorylation effectively impairs ATP production. This can lead to cellular injury and ultimately cell death if the hypoxic conditions persist.

In contrast, structures such as the Bowman capsule and the efferent arteriole are less metabolically active and do not rely on oxygen to the same extent as the proximal tubule, rendering them less susceptible to anoxic injury. The distal convoluted tubule also has lower energy requirements compared to the proximal tubule, focusing more on specific ion exchanges rather than the broad reabsorption tasks handled in the proximal region. Therefore, in scenarios of oxygen deprivation, the proximal tubule stands out as