– 2,3-Dinor-8-iso Prostaglandin F1α (2,3-dinor-8-iso PGF1α), an isoprostane and active metabolite of arachidonic acid deriving its formation from non-enzymatic free radical peroxidation, acts as an active metabolite of the platelet aggregation inhibitor 8-iso PGF2α. This compound exhibits vasoconstrictive properties in isolated porcine retinal and brain microvessels with EC50 values of 12.8 and 18.5 nM, respectively, yet it does not cause contraction in isolated rat aortic rings at a concentration of 31 µM. Further, at a concentration of 1 µM, it raises thromboxane B2 (TXB2) levels in isolated porcine brain slices, an effect reversible by thromboxane A synthase inhibitor CGS 12970, voltage-gated calcium channel inhibitor SKF 96365, or the nicotinic acetylcholine receptor (nAChR) antagonist α-conotoxin.