Cyclooxygenase 2 and the kidney

Cyclooxygenase metabolizes arachidonic acid to a family of bioactive fatty acids designated prostaglandins. Two isoforms of cyclooxygenase exist, desi gnated COX1 and COX2. These isoforms are expressed in distinct but importan t areas of the kidney. COX1 predominates in vascular smooth muscle and coll ecting ducts, whereas COX2 predominates in the macula densa and nearby cell s in the cortical thick ascending limb. COX2 is also highly expressed in me dullary interstitial cells. Whereas COX1 expression does not exhibit dynami c regulation, COX2 expression is subject to regulation by several environme ntal conditions, including salt intake, water intake, medullary tonicity, g rowth factors, cytokines, and adrenal steroids. Recently, COX2-selective no n-steroidal antiinflammatory drugs have become widely available. Many of th e renal effects of non-selective non-steroidal anti-inflammatory drugs (inc luding sodium retention, decreased glomerular filtration rate, and effects on renin-angiotensin levels) appear to be mediated by the inhibition of COX 2 rather than COX1. Therefore, in contrast to the gastro intestinal-sparing effects of COX2-selective non-steroidal anti-inflammatory drugs, when cons idering the kidney, the same caution must be applied when using COX2-select ive inhibitors as has been used with traditional non-selective non-steroida l anti-inflammatory drugs. Curr Opin Nephrol Hypertens 10:89-98. (C) 2001 L ippincott Williams & Wilkins.