Levels of Eicosanoids (6-oxo-pgf1" and 8-epi-pgf2") in Human and Porcine Lymphatics and Lymph

Prostaglandin (PG)I2 is the primary eicosanoid synthesized by human lymphatics and 8-epi-PGF2", an isoprostane formed during free radical catalyzed peroxidation, is the most potent stimulator of lymphatic contraction tested thus far. We now examine the respective concentrations in the lymphatic wall of both human and porcine lymphatics and lymph fluid using specific immunoassays. Although both compounds are detectable in the lymphatic wall and lymph fluid, PGI2(via its main metabolite 6-oxo-PGF1") is greater in the lymphatic wall whereas 8-epi-PGF2" dominates in lymph fluid. Because inflammation is associated with oxidative injury, which in turn stimulates release of isoprostane, eicosanoid derivatives may modulate lymphatic tone during acute tissue reaction. Prostaglandins (PG) are generated by lymphatics of various species. In human, PGI2, a potent antiaggregatory and vasodilatory eicosanoid (1), is a key metabolite found in the wall of lymphatics (2). Several eicosanoids are involved in modulating lymphatic contractility (3-5). The isoprostane 8-epi-PGF2", another eicosanoid stimulates smooth muscle contraction in various tissues (6,7) including lymphatics (8). Because isoprostanes (9) are the products of free radical catalyzed peroxidation of arachidonic acid, they accumulate during oxidative injury (10,11). Accordingly, the potential role of eicosanoids as modulators of lymphatic motility especially during inflammation is raised. As preliminary to future studies, we examined prostaglandin I2-formation (via the stable metabolite 6-oxo-PGF1") and the content of 8-epi-PGF2" in the wall of human and porcine lymphatics and their respective lymph fluid. MATERIALS AND METHODS