Effect of Elevated Uric Acid Concentrations on Different Metabolic and Regulatory Parameters of Human Endothelial Cells (HUVEC) in Culture

Abstract

Endothelial injury and loss of normal endothelial function are key events for the development of coronary heart disease (CHD), hypertension, diabetes, and atherosclerosis. As a part of metabolic syndrome hyperuricemia often accompanies these diseases. The aim of this study was to investigate whether interaction of uric acid with endothelial cells (HUVEC) alters their structural and functional integrity. Therefore, the cell monolayers were incubated with medium containing increasing concentrations of uric acid (250, 500, 1000 / ) for various times (0, 24, 48, 72, 96 hours) at 37 °C and 5% CO 2 in a humidified incubator. To assess the degree of endothelial injury we measured the kinetics of release of various enzymes (angiotensin-converting enzyme, lactate dehydrogenase, N-acetyl-ß-D-glucosaminidase) from the cells and the amount of thiobarbituric acid reactive substances (TEARS). Additionally, the functional integrity of HUVEC was estimated by measuring urateinduced changes of intracellular regulatory metabolites as nitrate/nitrite and neopterin. In conclusion, our study has demonstrated considerable modifications of biochemical markers of endothelial cell membrane permeability after incubation with elevated concentrations of uric acid. The extent of endothelial injury correlated with the uric acid concentration and the duration of the incubation period. Intracellular NOS activity and neopterin levels were affected to a lesser extent suggesting that functional integrity of HUVEC was not impaired in the experimental conditions used.