20-carboxy Arachidonic acid (20-COOH-AA) is the major metabolite of 20-HETE that is produced in renal tubular epithelial, endothelial, and microvascular smooth muscle cell cultures. This ω-oxidation conversion can take place using purified alcohol dehydrogenases three and four or by microsomes containing recombinant human CYP4F3B.¹ Like 20-HETE, 20-COOH-AA inhibits ion transport in the kidneys. It also produces vasorelaxation of porcine coronary microvessels constricted with endothelin. 20-COOH-AA binds to isolated ligand binding domains of peroxisome proliferator-activated receptor α (PPARα) (Kd = 0.87 ± 0.12 µM) and PPARγ (Kd = 1.7 ± 0.5 µM), and is a dual activator of PPARα and PPARγ in a transiently transfected COS-7 cell reporter system.¹