Figure 1
Relative hypoxia in the outer medulla predisposes to ischemic injury in the S3 segment of the proximal tubule. The thick ascending limb is also located in this hypoxic region of the kidney and, depending on tubular reabsorptive demand, may also undergo ischemic injury. The thick ascending limb may, however, be more protected against ischemic injury, because this nephron segment possesses more glycolytic machinery for ATP synthesis than the S3 segment.