Tanshinone IIA ameliorated endothelial dysfunction in rats with chronic intermittent hypoxia.

Chronic intermittent hypoxia (CIH) during repetitive airflow cessations may cause endothelial dysfunction. Tanshinone IIA (Tan IIA) has been used to treat various circulatory disturbance-related diseases because of its pharmacological actions, including vasodilation. However, the mechanism of the effect of its vasodilation is not well established. The objective of this study was to explore the effect of Tan IIA in endothelium-dependent contracting factors and endothelin receptors in aortic endothelial dysfunction in CIH rats. Aortas of rats were retrieved for use in in vitro experiments (isometric force measurement), histological analysis, immunohistochemistry, and Western blotting. Tan IIA treatment increased the expression of endothelial nitric oxide synthase (eNOS) and formation of nitric oxide (NO), inhibited the production of endothelin-1 (ET-1), down-regulated ET receptor expression, and up-regulated ET receptor expression. In conclusion, Tan IIA protects endothelial function by inhibiting strain-induced ET-1 expression, decreasing ET receptors, increasing ET receptors, increasing the formation of NO, and up-regulating eNOS in CIH.