20-HETE agonists and antagonists in the renal circulation

The present study examined the effects of a series of 20- hydroxyeicosatetraenoic acid (20-HETE) derivatives on the diameter of renal arterioles to determine the structural requirements of the vasoconstrictor response to 20-HETE. The vascular responses to 5-, 8-, 12-, 15-, 19-, 20-, 21-HETEs, arachidonic acid (AA), and saturated, partially saturated, dimethyl, carboxyl, and 19-carbon derivatives of 20-HETE (10^-8 to 10^-6 M) were assessed in rat renal interlobular arteries (65-125 μm). 20-HETE, 21- HETE, dimethyl-20-HETE, and a partially saturated derivative of 20-HETE, 20- hydroxyeicosa-5(Z),14(Z)-dienoic acid, reduced vessel diameter by 19 ± 3, 17 ± 3, 16 ± 2, and 28 ± 2%, respectively. In contrast, 5-, 8-, 12-, 15-, and 19-HETE, AA, saturated, partially saturated, carboxyl, and the 19-carbon derivatives of 20-HETE had no effect on vessel diameter. Pretreatment with 5- , 15-, and 19-HETE, the 19-carbon derivative or 20-hydroxyeicosa-6(Z),15(Z)- dienoic acid (1 μM) completely blocked the vasoconstrictor response to 20- HETE in renal arterioles. Pretreatment with AA, carboxyl, saturated 19- carbon, and saturated 20-HETE derivatives (1 μM) partially blocked the response, whereas 8- and 12-HETE (1 μM) had no effect on the vasoconstrictor response to 20-HETE. These findings suggest that 20-HETE agonists and antagonists require a carboxyl or an ionizable group on carbon i and a double bond near the 14 or 15 carbon. 20-HETE agonists also require a functional group capable of hydrogen bonding on carbon 20 or 21, whereas antagonists lack this reactive group.