Vascular dysfunction induced by AGE is mediated by VEGF via mechanisms involving reactive oxygen species, guanylate cyclase, and protein kinase C

Objective: These experiments were designed to elucidate mechanisms mediatin g, vascular dysfunction induced by advanced glycation end product, (AGEs), Methods: Skin chambers were mounted on the backs of Sprague-Dawley rats and 1 week later. granulation tissue that formed in the bottom of dir chamber was exposed twice daily for 7 days to glycated rat serum albumin in the pre sence and absence of inhibitors of reactive oxygen intermediates, nitric ox ide synthase and guanylate cyclase, protein kinase C (PKC). and a neutraliz ing vascular endothelial growth factor (VEGF) antibody. Vascular I-125-albu min clearance and blood flow were quantified by use Of a double isotope-dil ution technique and radiolabeled microspheres. respectively. Results: Albumin permeation and blood flow were increased dose-dependently to a maximum of 2 to 3 times controls by increasing, the extent of glucose modification, the concentration, or the duration of exposure to glycated al bumin, These increases were significantly attenuated by probucol and supero xide dismutase, N-G-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase inhibitor. LY83583, a guanylate cyclase inhibitor, and LY333531, a beta -isoform-selective protein kinase C inhibitor. A neutralizing VEGF mo noclonal antibody also markedly attenuated the permeability and blood flow increased induced by glycated albumin. Conclusions: These observations indicate potentially important role,, for o xygen free-radicals and nitric oxide in mediating permeability and blood fl ow changed induced by glycated proteins via mechanisms involving increased protein kinase C activity and VEGF production. Striking similarities in the mechanism by which hyperglycemia and glycated proteins induce vascular dys function suggest that a common pathway mediates effects of these different metabolic imbalances on vascular dysfunction.