Electrolyte and fluid transport in the kidney are regulated in part by arachidonic acid and its metabolites. (±)16-HETE is the racemic version of a minor CYP450 metabolite of arachidonic acid released by the kidney upon angiotensin II stimulation. The biological activity of 16-HETE is stereospecific. 16(R)-HETE dose-dependently stimulates vasodilation of the rabbit kidney, however 16(S)-HETE does not affect perfusion pressure. At a concentration of 2 μM the (S)-enantiomer of 16-HETE inhibits proximal tubule ATPase activity by as much as 60%, whereas the (R)-isomer has negligible effects on ATPase activity.