Renal and cardiovascular actions of 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids

1. Arachidonic acid (AA) is metabolized by cytochrome P450 (CYP)-dependent pathways to epoxyeicosatrienoic acids (EET) and 20-hydroxyeicosatetraenoic acid (20-HETE) in the kidney and the peripheral vasculature. 2. The present short review summarizes the renal and cardiovascular actions of these important mediators. 3. Epoxyeicosatrienoic acids are vasodilators produced by the endothelium t hat hyperpolarize vascular smooth muscle (VSM) cells by opening Ca2+-activa ted K+ (K-Ca) channels. 20-Hydroxyeicosatetraenoic acid is a vasoconstricto r that inhibits the opening of K-Ca channels in VSM cells. Cytochrome P450 4A inhibitors block the myogenic response of small arterioles to elevations in transmural pressure and autoregulation of renal and cerebral blood flow in vivo. Cytochrome P450 4A blockers also attenuate the vasoconstrictor re sponse to elevations in tissue PO2, suggesting that this system may serve a s a vascular oxygen sensor. Nitric oxide and carbon monoxide inhibit the fo rmation of 20-HETE and a fall in 20-HETE levels contributes to the activati on of K-Ca channels in VSM cells and the vasodilator response to these gase ous mediators. 20-Hydroxyeicosatetraenoic acid also mediates the inhibitory actions of peptide hormones on sodium transport in the kidney and the mito genic effects of growth factors in VSM and mesangial cells. A deficiency in the renal production of 20-HETE is associated with the development of hype rtension in Dahl salt-sensitive rats. 4. In summary, the available evidence indicates that CYP metabolites of AA play a central role in the regulation of renal, pulmonary and vascular func tion and that abnormalities in this system may contribute to the pathogenes is of cardiovascular diseases.