Eicosanoids in bovine retinal microcirculation

The vasoactive effects of the arachidonic acid-derived cyclooxygenase product, prostaglandin F-2 alpha and PGH(2) analogue U46619, on ex vivo perfused (25 mu l/min) bovine retinal microcirculation were assessed. First, we determined the ability of the cultured bovine retinal microvascular endothelial cells to synthesize eicosanoids from C-14-arachidonic acid. Bovine retinal microvascular endothelial cell cultures synthesized detectable amounts of PGE(2), PGF(2 alpha), PGI(2), and PGH(2) analogue; PGI(2) product being slightly greater. The central retinal arteriole was cannulated and microcirculation continuously perfused with PSS with constant flow. Vasoactive compounds were applied in ten-fold concentration increments to PSS in the muscle chamber containing retinal preparation. The diameters of retinal microarterioles were measured using a closed-circuit video camera system. In ex vivo bovine retinal microvascular model studies, PGF(2 alpha) and PGH(2) analogue U46619, caused dose-dependent vasoconstriction of all vessels, and these responses were attenuated by specific TP (TXA(2)) receptor antagonist, SQ 29,548, at 10(-6) M.