FORMATION OF AN F-2-ISOPROSTANE IN VASCULAR SMOOTH-MUSCLE CELLS BY ELEVATED GLUCOSE AND GROWTH-FACTORS

Recently a series of non-cyclooxygenase-derived prostanoids were ident ified in vivo in humans and in animal models of free radical injury as products of free radical-catalyzed peroxidation of arachidonic acid. One of these, an F-2-isoprostane, 8-epiprostaglandin F-2 alpha (8-epi- PGF(2 alpha)), is a potent renal vasoconstrictor and can increase vasc ular smooth muscle cell (VSMC) DNA synthesis. In the present study we have evaluated whether F-2-isoprostanes play a role in diabetic vascul ar dysfunction by studying the formation of 8-epi-PGF(2 alpha) in porc ine VSMC (PVSMC) cultured under hyperglycemic conditions. 8-Epi-PGF(2 alpha) levels were quantitated by a specific enzyme immunoassay. We al so examined whether certain VSMC growth factors, such as angiotensin I I, platelet-derived growth factor, and transforming growth factor-beta , could also regulate the formation of 8-epi-PGF(2 alpha). We observed that PVSMC cultured under high glucose (HG) conditions produced signi ficantly higher amounts of 8-epi-PGF(2 alpha) compared with normal glu cose (NG) conditions (3.7 +/- 0.13 ng/10(6) cells in HG vs. 2.9 +/- 0. 2 ng/10(6) cells in NG, P < 0.05). Furthermore, all three growth facto rs tested evoked significant dose-dependent formation of 8-epi-PGF(2 a lpha) (ranging from 125 to 220% of control). These results suggest tha t 8-epi-PGF(2 alpha) formation, as a result of hyperglycemia or due to growth factor action, may lead to increased VSMC growth and contribut e to the complications of diabetes and cardiovascular disease.