乳清蛋白防治高血压及其机制研究

血管紧张素I（AngI）在血管紧张素转换酶（ACE）作用下生成Ang II，激活血管平滑肌细胞（VSMC）的p63RhoGEF（速度快，作用于基础血压）和p115RhoGEF（速度慢，作用于高血压），升高血压。乳品技术水解牛奶蛋白得到许多抑制ACE的活性肽，我们也发现牛奶活性肽的降压作用。那么，1)摄取乳清蛋白（非水解活性肽）是否同样有降压效果？2) 作用迥异的p63RhoAGEF和p115RhoGEF在乳清蛋白降压中作用如何？本项目采用乳清蛋白喂养自发高血压大鼠和乳清蛋白与诱导高血压的D-果糖溶液同时喂养大鼠，动态观察血压、血液ACE活力、心血管和肾功能，并比较RhoGEF通路的蛋白表达。为了在细胞水平上研究乳清蛋白消化吸收后的作用，我们用动物血浆提取物干预VSMC，探讨两个RhoGEF通路的mRNA和蛋白表达。本项目研究乳清蛋白本身防治高血压及机制，具有重要的理论和现实意义。

Angiotensin I (AngI) can be converted to Angiotensin II (AngII) by angiotensin converting enzyme (ACE) and finally hypertension occurs through multipal RhoA GTP exchange factors (GEFs) including p63RhoGEF (early signal transduction, predominantly control basal blood pressure) and p115RhoGEF (late signal transduction, act on pathological hypertension) in vascular smooth muscle cells (VSMCs). A number of bioactive peptides, which have the ability to inhibit ACE, have been identified by hydrolyzing enzyme using dairy technology. Our meta-analysis of randomized controlled trials also found that lactotripeptides intake resulted in a statistically significant blood pressure reduction. Thus, our questions are 1) does the intake of whey protein (not milk-derived peptides) exhibit hypotensive effects? 2) how does different RhoGEF of p63RhoGEF and p115RhoGEF play the roles to control blood pressure? Therefore, the current project applying to NSFC plans to investigate the hypotensive effects of whey protein and its possible mechanism from the aspects of prevention and treatment. In animal studies, spontaneously hypertensive rat (SHR) will be fed with whey protein to observe the hypotensive effects. At the same time, SD rats will be fed with whey protein during the induced-hypertension by drink of D-fructose to observe the control of blood pressure. Blood pressure, plasma ACE activity and vascular reactivity are measured at the time course. The protein expression of two RhoGEFs in artery is also analyzed. On the other hand, to study in vivo the effects of whey protein after digestion and absorption, the plasma extract from rats feeding whey protein will be used as intervention in vascular smooth muscle cell (VSMC). Cellular morphology, cell proliferation, cell cycles and ACE activity in culture supernatant are determined. Furthermore, the expression of mRNA and protein in pathway of p63RhoGEF and p115RhoGEF is extensively studied. Considering the common consumption of milk and high prevalence of hypertension, our project is importance for theory and practice.