Study On The Effect Of The Crude Extracts Of Herba Lysimachiae-Induced Relaxation In Rat Aorta

Diabetes mellitus is metabolic diseases characterized by hyperglycaemia, for which is the loss of insulin secretion or(and) the reduction of insulin physiological function. The diabetic map of the International Diabetes Federation(IDF) shows that the number of diabetes in China is still the largest in the world in 2015. Permanent high blood glucose leads to various injury including the heart, blood vessels, eyes, kidney, nerve chronic injury and dysfunction. Therefore,how to reduce cardiovascular risk in diabetes management is a hot topic in clinic. Vascular endothelial dysfunction, mainly represented by the reduction of vasorelaxation, is a major characteristic to the cardiovascular complication of diabetes. Herba Lysimachiae which is Lysimachia christinae Hance in Primulaceae is the fresh or dry herb to protect liver and gall bladder, promote the excretion of urine and renal calculus. It also has the efficacy of anti-inflammation. Studies show that extracts of Herba Lysimachiae have potent to scavenge active oxygen species, which are used to treat angina and cerebral arteriosclerosis. However, there is little study for vasodilation of the Herba Lysimachiae. Thus, the experiment was designed to screen the extracts which had the effect of vasorelaxation in Herba Lysimachiae and discussed its mechanism with thoracic aorta rings.Objectives:To explore the relaxation effect and mechanism of the crude extracts of Herba Lysimachiae in rat aortic rings.Methods:SD rats, male(250 g ~300 g), were anesthetized with chloral hydrate(400 mg kg-1, i.p.) and sacrificed by cervical dislocation. The descending thoracic aorta was rapidly isolated and suspended in a Multi Myograph System and set the initial tension(1.0~1.5 g). After 90 minutes, phenylephrine(0.5 μmol/L, PE) was given to contract these rings and crude extracts from Herba Lysimachiae(ethyl acetate extracts, ligarine extracts, n-butanol extracts and water extracts) were concentration-accumulatively(0.01, 0.03, 0.1, 0.3, 1 g/L) added. In some experiments, endothelial cells of aorta rings was denuded or rings with endothelium were pre-incubated with L-NAME(100 μmol/L, e NOS inhibitor), which was to evaluate the effect of endothelium on the relaxation induced by extracts of Herba Lysimachiae.Results:Ethyl acetate extracts(1 g/L) erived from Herba Lysimachiae had the potent dilating effect although water extracts, n-butanol extracts, and ligarine extractsd can relaxe aorta rings. Furthermore, ethyl acetate extracts produced a dose-dependent relaxation in rat aortic rings with endothelia, as only caused slightly dilation in aortic rings without endothelia. Additionally, in the presence of L-NAME obviously blunt the relaxation in rat aortic rings caused by ethyl acetate extracts.Conclusion:Ethyl acetate extracts of Herba Lysimachiae can dilate aorta rings in rats, which may be involved in activating endothelial nitric oxide synthase(e NOS) to release nitric oxide(NO).