Abstract 208: Improved Vasodilatory Function in Ins2Akita Type 1 Diabetic Mice with Daily Intake of Oral L-Arginine in Combination with Salsalate

Abstract

Endothelial dysfunction due to deficient nitric oxide (NO) generation cause progressive vascular complications in diabetes. Our earlier findings revealed that Inhibitor kappa B kinase beta (IKK-beta) -an upstream regulator of an inflammatory mediator, nuclear factor kappa-B (NF-kB), competitively inhibits endothelial nitric oxide synthase (eNOS), the chief source of NO in blood vessels. Therefore, we investigated the influence of an inhibitor of IKK beta, salsalate in augmenting eNOS activity. The co-operative effect of L-arginine supplementation (substrate of eNOS) with salsalate intake in enhancing eNOS activity has been evaluated. Both in vitro cell cultures and diabetic/transgenic animal models were used. Human aortic endothelial cells incubated with 25 mM glucose with or without L-arginine (2mM), the cofactor sepiapterin (100uM) and salsalate(50uM) were examined for NO production. Combined L-arginine and salsalate treatment enhanced NO production, phospho eNOS expression and eNOS-dimer vs monomer ratio. For in vivo assays, diabetic Ins2Akita mice were fed with L-arginine and salsalate for 15 weeks. Aortae of these mice exhibited increased phospho eNOS expression and increased eNOS dimer/monomer ratio. Arterial ring assays showed improved acetylcholine mediated vasodialation. Transgenic-Akita mice that overexpress human eNOS in endothelial cells (Tie-2eNOS-Ins2 Akita) generated in-house showed improved vasodialation. In conclusion, enhancing eNOS activity in diabetic mice either by genetic modification as seen in Tie-2 eNOS-Akita mice or by nutritional approach (supplementation of L-arginine with simultaneous inhibition of IKK beta) restores normal vasodialatory function.