After experiencing vasodilation and hypotension from anaphylaxis, which kidney area is most likely injured?

In the case of anaphylaxis leading to vasodilation and hypotension, the correct answer pertains to the proximal tubules of the kidney. During a significant drop in blood pressure, renal perfusion is compromised, which can lead to acute kidney injury. The proximal tubules are particularly sensitive to ischemia and reduced blood flow.

Proximal tubular cells are responsible for a significant amount of solute and water reabsorption, and they have a high metabolic demand due to their active transport processes. When there is insufficient blood flow due to hypotension, these cells may not receive adequate oxygen and nutrients, resulting in cellular injury or death.

In contrast, the glomerular epithelial cells, while crucial for filtration, tend to be more resilient in the face of acute changes in blood flow compared to tubular cells. The Loop of Henle and the medullary interstitium may also sustain injury; however, the proximal tubules are generally seen as the first area to be affected during a significant reduction in kidney perfusion due to their metabolism-dependent functions.

Thus, in an anaphylactic event leading to hypotension, the proximal tubules are the most likely site of injury due to their vulnerability to ischemic conditions.