Galen M. Pieper

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The present experiments were conducted to determine whether endothelium-dependent relaxation is impaired in chronic (10-12 wk), streptozotocin-induced diabetic rat aortas and to determine the specificity and sensitivity of diabetic vasculature to oxygen-derived free radicals. Endothelium-dependent relaxation by acetylcholine and ADP was severely impaired in(More)
  • G M Pieper
  • Journal of cardiovascular pharmacology
  • 1997
Tetrahydrobiopterin is a cofactor for nitric oxide synthase. In low concentrations of this cofactor, nitric oxide synthase is known to produce less nitric oxide and, correspondingly, enhanced quantities of the oxidant species, hydrogen peroxide. In this study, we tested the hypothesis that an exogenous tetrahydrobiopterin derivative might improve(More)
Nitric oxide release from the endothelium plays an important role in regulation of vascular tone, inhibition of both platelet and leukocyte aggregation and adhesion, and inhibition of cell proliferation. These properties suggest that the level of NO production by the endothelium may play a pivotal role in the regulation of vascular disease. Analysis using(More)
Long-term diabetes mellitus is characterized by impaired endothelium-dependent relaxation. In contrast, there is limited information on endothelial function in the early stages of the disease. In this study, we evaluated endothelial function ex vivo at early, intermediate and later stages of streptozotocin (STZ)-induced diabetes mellitus. We also evaluated(More)
OBJECTIVE Previous studies suggest a role of superoxide anion radicals (.O2-) in impaired endothelium-dependent relaxation of diabetic blood vessels; however, the role of secondary reactive oxygen species remains unclear. In the present study, we investigated a role of various potential reactive oxygen species in diabetic endothelial dysfunction. METHODS(More)
Defective endothelium-dependent relaxation in diabetic blood vessels may be regulated at the site of synthesis. We tested the hypothesis that acute administration of L-arginine (L-Arg) as substrate for endothelium-derived relaxing factor (EDRF) would normalize defective relaxation to acetylcholine (ACh) in streptozotocin-induced diabetic rat aortic rings.(More)
Arginine is a precursor amino acid for the synthesis of nitric oxide by nitric oxide synthase. A defect in arginine supply could regulate nitric oxide-mediated, endothelium-dependent relaxation. In this study, we evaluated the effect of supplementation with L-arginine given in vitro on both functional relaxation and cGMP generation in response to(More)
Electron spin resonance (ESR) spectroscopy together with spin trapping techniques and the application of state-of-the-art loop gap resonators was used to provide a direct measure of spontaneous oxygen radical production by homogenates of freshly isolated and cultured rat pancreatic islets. Using the spin trap agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO),(More)
Oxidative stress is important in the pathogenesis of renal ischemia-reperfusion (IR) injury; however whether imbalances in reactive oxygen production and disposal account for susceptibility to injury is unclear. The purpose of this study was to compare necrosis, apoptosis, and oxidative stress in IR-resistant Brown Norway rats vs. IR-susceptible(More)
Brief (15-minute) coronary occlusion and subsequent reperfusion lead to prolonged functional and metabolic abnormalities (stunned myocardium). Previous work suggests that one factor responsible for this phenomenon is oxygen-derived free radicals. The formation of the highly reactive hydroxyl radical requires the presence of metal ions, most importantly(More)