Increased aortic stiffness elevates pulse and mean pressure and compromises endothelial function in Wistar rats

Abstract

An increase in pulse pressure (PP) is highly associated with hypertension. The goal of this study was to determine the effect of increased aortic stiffness on PP and endothelial dysfunction as precursors to hypertension. A rat model of suddenly increased aortic stiffness by use of a nonconstrictive restraint (glue coating) on aortic surface was created to investigate the change of PP and mean arterial pressure (MAP). Group I ( n = 16) underwent aorta restraint for 4 wk. Group II ( n = 12) underwent aortic restraint for 4 wk, followed by restraint removal to evaluate extent of reversibility for additional 4 wk. The aortic and peripheral endothelial function was assessed by ACh-stimulated endothelium-dependent vasodilation. The level of nitrate/nitrite (NOx), endothelin-1 (ET-1), and prostacyclin (PGI2) were measured in the serum and artery tissue. We found that aortic stiffening causes a significant increase in PP and MAP ( P < 0.05). The endothelial function was markedly blunted ( P < 0.05) in both aorta and small peripheral artery. After removal of the restraint, the impaired endothelium function persisted in the aorta likely due to sustained deterioration of aortic wall, but was partially restored in peripheral artery. The endothelial dysfunction was correlated with a decrease in NOx and PGI2 ( P < 0.05) and an increase in ET-1 ( P < 0.05). Our results show that aortic stiffening results in widening of PP, which affected endothelium function through changes in synthesis of NOx, ET-1, and PGI2. These findings suggest that increased aortic stiffness may be a cause of increased PP and a precursor to hypertension.