Renal hemodynamic actions of lipoxins in rats: A comparative physiological study

Interactions between either the arachidonate 5-lipoxygenase (5-LO) and 15-LO or 5-LO and 12-LO can lead to the formation of lipoxins. Although the functional significance of lipoxygenase products of arachidonic acid has been recognized increasingly in glomerular inflammation, less is known regarding the specific effects of lipoxins on renal hemodynamics. Here, we examine the renal actions of lipoxin (LX) A₄, LXB₄, and, the recently identified 7-cis-11-trans-LXA₄, which were administered into the renal artery of the euvolemic male Munich-Wistar rat. LXA₄ caused increases in renal plasma flow (RPF) and glomerular filtration rate (GFR) in a dose-dependent manner. These effects were reversed during cyclooxygenase inhibition. LXB₄ decreased both RPF and GFR, and its mode of action was independent of cyclooxygenase activity. 7-cis-11-trans-LXA₄ decreased RPF and GFR, which effects were abolished during systemic infusion of the leukotriene D₄ receptor antagonist SKF 104353. Results indicate that each of these lipoxins displays distinct hemodynamic effects via a specific mode of action on the renal vasculature of rats. Moreover, they suggest mechanisms whereby lipoxins may participate in the changes of renal hemodynamics that occur during glomerular inflammatory processes.