Hypoxia of the Renal Medulla — Its Implications for Disease

In land mammals, a major task of the kidney is to reabsorb water to allow survival in a dry environment. Water conservation is enhanced by the renal medulla, which concentrates the urine to a level up to four times the osmolality of plasma. To produce this unique gradient of osmolality, the medulla has a countercurrent system of vessels and tubules that dictates active reabsorption of sodium in a milieu poor in oxygen (Figure 1). 1 In this review, we describe how hypoxia of the medulla may relate to susceptibility to acute and chronic renal injury. The Renal Medullary Concentrating Mechanism as . . .