Experimental study of blood pressure and its impact on spontaneous hypertension in rats with Xin Mai Jia.

Aim: The aim of this study was to evaluate the antihypertensive effect of Xin Mai Jia (XMJ) and to explore the mechanism of its hypotensive effect.

Methods: A total of 50 spontaneously hypertensive rats (SHR) were randomised into five groups. A total of 30 Wistar-Kyoto rats were randomised into three groups, comprising the control group. All of the rats were administered medicine through a gastrogavage once a day for 8 weeks. The tail-cuff method was applied to their monitor blood pressure. After 8 weeks of treatment, serum NO, SOD activity, MDA level, ET, ALD, AngII, RE, and CGRP in the serum were detected in all of the rats. Pathological changes in the aorta were observed via haematoxylin-eosin (HE) and immunohistochemical staining. Vasodilation function was assessed by measuring acetylcholine-induced vessel relaxation in the rats' organ chambers. The function of the mesenteric arteries was measured using DMT wire myography. Human aortic smooth muscle cells (HASMCs) and human umbilical vein endothelial cells (HUVECs) injury models were induced by hydrogen peroxide (HO). HASMCs and HUVECs were injured by HO and then exposed to various drugs. HASMC and HUVEC migration was evaluated using the cell scratch test. The expression of the AT1 receptors (AT1R) in the HASMCs was detected via immunofluorescence (IFC) assay.

Results: After 8 weeks of treatment, XMJ reduced the systolic blood pressure of the SHR. XMJ significantly reduced the serum RE, AngII, ALD, and ET-1 levels and increased the content of CGRP and NO in the SHR, upregulated the SOD content, and downregulated MDA level of the SHR. XMJ improved pathological damage of the aorta to varying degrees, decreased the expression of AT1R in the SHR aortic vessels, and improved the mesenteric microvascular relaxation of the SHR. Cell experiments confirmed that XMJ inhibited the migration of the HUVECs and HASMCs induced by HO and the expression of AT1R in the HASMCs.

Conclusion: XMJ had satisfactory hypotensive action on the SHR in this study. Its mechanism may be associated with inhibiting RAAS activity and improving RAAS function, inhibiting hypertensive-induced vascular diastolic dysfunction, and improving vascular endothelial function.