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 viv o perfused (25 mu l/min) bovine retinal microcirculation were assessed . First, we determined the ability of the cultured bovine retinal micr ovascular endothelial cells to synthesize eicosanoids from C-14-arachi donic acid. Bovine retinal microvascular endothelial cell cultures syn thesized 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 w ith PSS with constant flow. Vasoactive compounds were applied in ten-f old concentration increments to PSS in the muscle chamber containing r etinal preparation. The diameters of retinal microarterioles were meas ured using a closed-circuit video camera system. In ex vivo bovine ret inal microvascular model studies, PGF(2 alpha) and PGH(2) analogue U46 619, 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.