Abstract 884: AGE/RAGE Produces Endothelial Dysfunction in Coronary Arterioles in Type II Diabetic Mice
The interaction of advanced glycation end products (AGE) with its receptor (receptor for AGE [RAGE]) stimulates the production of superoxide. AGE/RAGE signaling in vascular tissue would increase oxidative stress and impair the bioavailability of nitric oxide (NO). Accordingly, we hypothesized that impaired NO-dependent dilation (endothelial dysfunction) in type II diabetes results, in part, from elevated production of superoxide induced by AGE/RAGE signaling. To test this hypothesis, we assessed the role of AGE/RAGE signaling in endothelial dysfunction in type II diabetic (Leprdb) mice by evaluation of endothelial function of isolated coronary resistance vessels of m Leprdb (heterozygote, normal) and Leprdb (homozygote, diabetic) mice. Coronary arterioles (40 –100 μm) were isolated and pressurized (60 cmH2O) without flow. Although dilation of vessels to the endothelium-independent vasodilator, sodium nitroprusside (SNP) was not different between Leprdb and m Leprdb mice (n = 6), dilation to the endothelium-dependent agonist, acetycholine (ACh) was reduced in Leprdb vs m Leprdb (maximal dilation of 22 ± 3% vs 90.8 ± 2.4%, respectively, P < 0.05). Administration of the decoy, soluble RAGE (sRAGE, 80 μg/day, 10 days, i.p.; to antagonize RAGE signaling), signficantly increased dilation in Leprdb mice (67.6 ± 2.7% maximal dilation) vs Leprdb without treatment (P < 0.05), but did not affect dilation in m Leprdb mice. Competitive-ELISA indicated serum AGE production dramatically increased in Leprdb mice and real-time PCR and Western analyses showed higher expression (P < 0.05) of RAGE mRNA and protein expression. Immunostaining indicated that the expression of RAGE in coronary arterioles was markedly increased in both endothelial and vascular smooth muscle in Leprdb vs m Leprdb mice. Real-time PCR and Western results indicated that mRNA and protein expression of NAD(P)H oxidase subunit including gp91/NOX2, p22-phox and p40-phox increased in Leprdb mice compared to m Leprdb mice. However, sRAGE significantly inhibited the expression of NAD(P)H oxidase. These results indicate that AGE/RAGE signaling plays a pivotal role in endothelial oxidative stress and dysfunction in type II diabetes.