Physiologic and pathophysiologic roles of lipid mediators in the kidney.

Small lipids such as eicosanoids exert diverse and complex functions. In addition to their role in regulating normal kidney function, these lipids also play important roles in the pathogenesis of kidney diseases. Cyclooxygenase (COX)-derived prostanoids play important role in maintaining renal function, body fluid homeostasis, and blood pressure. Renal cortical COX2-derived prostanoids, particularly (PGI2) and PGE2 play critical roles in maintaining blood pressure and renal function in volume contracted states. Renal medullary COX2-derived prostanoids appear to have antihypertensive effect in individuals challenged with a high salt diet. 5-Lipoxygenase (LO)-derived leukotrienes are involved in inflammatory glomerular injury. LO product 12-hydroxyeicosatetraenoic acid (12-HETE) is associated with pathogenesis of hypertension, and may mediate angiotensin II and TGFbeta induced mesengial cell abnormality in diabetic nephropathy. P450 hydroxylase-derived 20-HETE is a potent vasoconstrictor and is involved in the pathogenesis of hypertension. P450 epoxygenase derived epoxyeicosatrienoic acids (EETs) have vasodilator and natriuretic effect. Blockade of EET formation is associated with salt-sensitive hypertension. Ceramide has also been demonstrated to be an important signaling molecule, which is involved in pathogenesis of acute kidney injury caused by ischemia/reperfusion, and toxic insults. Those pathways should provide fruitful targets for intervention in the pharmacologic treatment of renal disease.