Figure 2.

Intrarenal localization of cyclooxygenases (COXs), prostaglandin E (PGE) synthases, and PGE₂ receptors EP1-4 throughout the nephron and collecting duct system. COX-1 is constitutively expressed in the glomerulus, afferent arteriole, proximal tubule, vasa recta, collecting duct, and medullary interstitial cells. COX-2 is expressed in the glomerulus, proximal tubule, thick ascending limb, macula densa, collecting duct, and medullary interstitial cells. Microsomal PGE synthase-1 (mPGES-1) is mainly localized in the macular densa, collecting duct and medullary interstitial cells. mPGES-2 is abundant in the proximal tubule, thick ascending limb, and distal tubule, while Microsomal PGE synthase-1 (mPGES-1) is expressed predominantly in the collecting ducts. EP1 is expressed in the collecting duct predominantly, and also in the glomerular podocytes and mesangial cells. EP2 has low levels of expression in the kidney, and it present only in the vasa recta and collecting duct. EP3 expression appears to be primarily localized in the thick ascending limb and collecting duct, with low expression in the glomerulus, afferent arteriole, distal tubule, and macula densa. EP4 is predominantly expressed in the glomerulus and collecting ducts, but also detected in other renal tubular segments. G, glomerulus; AA, afferent arteriole; PT, proximal tubule; TAL, thick ascending limb; VR, vasa recta; DT, distal tubule; MD, macula densa; CD, collecting duct; RMIC, renal medullary interstitial cell.