ELEVATED GLUCOSE AND ANGIOTENSIN-II INCREASE 12-LIPOXYGENASE ACTIVITYAND EXPRESSION IN PORCINE AORTIC SMOOTH-MUSCLE CELLS

The lipoxygenase (LO) pathway of arachidonate metabolism has been sugg ested to play a key role in atherosclerosis and in mediating several a ctions of angiotensin II (AII). However, the relationship between LO a ctivation and factors linked to accelerated diabetic vascular disease such as hyperglycemia and AII is not known. We have investigated the e ffect of high glucose (HG; 25 mM) and AII on LO activity as well as LO protein and mRNA expression in porcine aortic vascular smooth muscle cells (PVSMCs). We observed that cells cultured in HG had significantl y higher levels of the cell-associated LO products 12- and 15-hydroxye icosatetraenoic acids (HETEs). AII added to cells grown in HG specific ally further increased only cell-associated 12-HETE levels. Using immu noblot analysis and reverse transcriptase PCRs, we demonstrated the pr esence in PVSMCs of porcine leukocyte-type 12-LO protein and mRNA, res pectively. Furthermore, the levels of both were markedly upregulated b y AII as well as by HG. These studies suggest that enhanced 12-LO acti vity and expression are mechanisms for accelerated vascular disease pr oduced by HG and AII in diabetes mellitus.