[775][776][777][778][779][780] 2003) have provided compelling evidence that cytochrome P-450-derived EETs have antihypertensive properties and are endothelially derived hyperpolarizing factors (EDHFs) in the kidney. EETs also possess anti-inflammatory actions that could protect the kidney vasculature from injury during renal and cardiovascular diseases. A tactic that has been used to increase EET levels has been inhibition of the soluble epoxide hydrolase enzyme. Epoxide hydrolase inhibitors have been demonstrated to be antihypertensive and renal protective. Thus the renal and cardiovascular protective actions of increasing epoxygenase levels could be translated to therapies for preventing end-organ damage. epoxyeicosatrienoic acids; endothelium-derived hyperpolarizing factor; hypertension; nephropathy; inflammation A MAJOR CAUSE OF MORBIDITY and mortality is the progression of organ damage associated with renal and cardiovascular diseases. For instance, the incidence of end-stage renal disease (ESRD) is escalating and the number of patients on dialysis is predicted to double over the 10-yr period of 2000 -2010 (7, 9, 19, 34, 104). The two main diseases responsible for the increase in ESRD are diabetes and hypertension. One contributing factor to end-organ damage is an impaired endothelium (6,21,56,60,95). Interestingly, endothelial dysfunction has recently been touted as a marker for unfavorable cardiovascular prognosis in humans (5,27,66). Others and we have established that cytochrome P-450 (CYP) metabolites (CYP2C) produced by the endothelium have antihypertensive properties and proposed that the epoxyeicosatrienoic acids (EETs) are endothelium-derived hyperpolarizing factors (EDHFs) (2,12,30,43,50,87). Additionally, EETs have profibrinolytic effects, anti-inflammatory actions, and inhibit smooth vascular muscle cell migration (11,20,32,78,79,94). Recent interest has also focused on the role of soluble epoxide hydrolase (SEH) in renal and cardiovascular disease and inhibition of this enzyme as an avenue to increase EET levels. This review will highlight these favorable EET properties that could protect the kidney from ESRD during renal and cardiovascular disease states.
EPOXYGENASE METABOLITES AS AN EDHF AND BEYONDThe contribution of the endothelial cells to the control of blood flow has been recognized for over two decades. Earlier studies established that endothelium-derived factors could act on vascular smooth muscle cells to relax or contract arteries (38,68). The identity of nitric oxide and prostaglandins as the main products of the endothelial cells that relax the vascular smooth muscle has been well established (10,38,67,68). In addition, the fact that the endothelium released one or more substances that relaxed vascular smooth muscle cells through membrane hyperpolarization was also repeatedly demonstrated (10,67,95). A number of studies have provided evidence that this nitric oxide-and cyclooxygenase (COX)-independent endothelium-derived relaxing factor was a metabolite of the arachidonic acid c...