The purpose of this chapter is to review the current state of knowledge concerning the microcirculation of the renal medulla. This is a broad topic that touches on many areas. Perhaps the best recognized function of descending and ascending vasa recta (DVR and AVR) is to trap solute through countercurrent exchange. The classical notions of diffusive exchange have been revised to account for endothelial expression of aquaporin-1 water channels and the UTB-facilitated urea carrier. In addition to transport-related functions, DVR are contractile microvessels that regulate regional perfusion of the medulla. Medullary perfusion is of great importance, not only to the urinary concentrating mechanism but also to the maintenance of oxygen tension and renal salt handling. Evidence has accumulated that reduction of medullary perfusion can be accompanied by ischemic insult because oxygen tensions in the renal medulla are particularly low. Also of great interest is the finding that reduction of perfusion can lead to experimental forms of hypertension.

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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