Cardiovascular and renal hemodynamics and the DASH diet

描述（由申请人提供）：本申请提出扩展DASH研究的发现，该研究表明，强调水果、蔬菜和低脂乳制品的饮食模式以及总脂肪和饱和脂肪的总体减少显著降低血压（BP）。DASH饮食对非裔美国人和收缩期高血压患者特别有效。然而，我们不知道DASH饮食是否会影响高血压过程的病理生理学。我们的初步数据支持DASH饮食中断肾素-血管紧张素系统的可能性。这提出了一个有趣的可能性，即DASH饮食将对单纯收缩期高血压患者的心血管和肾脏血流动力学产生有利影响。因此，本申请的中心假设是，DASH饮食通过降低组织肾素-血管紧张素系统活性来影响中心主动脉僵硬度、舒张期舒张以及肾和血管对血管紧张素II（Ang II）的反应性。我们将在单纯收缩期高血压患者中检验这一假设，通过确定DASH饮食是否（1）降低中心主动脉僵硬度（通过特征阻抗（Zc）和颈动脉-股动脉脉搏波速度（CF-PWV）测量），（2）改善舒张期舒张，通过舒张早期心肌速度（Ea）测量，（3）血管舒张肾血流并增强肾和血管对Ang II的反应，和（4）以类似于ACE抑制的方式影响这些血液动力学参数。我们将对55名患有单纯收缩期高血压的参与者进行随机交叉喂养研究，研究DASH饮食和对照饮食。参与者将进入对照饮食的2周导入期，随后是以随机顺序吃对照饮食或DASH饮食的两个6周喂养期。在每个喂养期后，将在给予卡托普利之前和之后测量导管血管血液动力学测量、舒张期舒张以及肾和血管对Ang II的反应。这些研究的结果将确定DASH饮食是否对高血压过程改变的机制产生有利影响，包括心血管风险较高的一组个体的肾脏和心脏功能。

DESCRIPTION (provided by applicant): This application proposes to expand upon the findings of the DASH study, which showed that a dietary pattern emphasizing fruits, vegetables and low fat dairy products and is overall reduced in total and saturated fat significantly lowers blood pressure (BP). The DASH diet is particularly effective in African Americans and in individuals with systolic hypertension. However, we do not know if the DASH diet affects the pathophysiology of the hypertensive process. Our preliminary data support the possibility that the DASH diet interrupts the renin-angiotensin system. This raises the intriguing possibility that the DASH diet will favorably impact on cardiovascular and renal hemodynamics in patients with isolated systolic hypertension. Therefore, the central hypothesis of this application is that the DASH diet affects central aortic stiffness, diastolic relaxation and renal and vascular reactivity to angiotensin II (Ang II) by lowering tissue renin-angiotensin system activity. We will test this hypothesis in patients with isolated systolic hypertension, by determining if the DASH diet (1) reduces central aortic stiffness, as measured by characteristic impedance (Zc) and carotid-femoral pulse wave velocity (CF-PWV), (2) improves diastolic relaxation, as measured by early diastolic myocardial velocities (Ea), (3) vasodilates renal blood flow and enhances the renal and vascular response to Ang II, and (4) affects these hemodynamic parameters in a manner that is similar to ACE inhibition. We will study 55 participants with isolated systolic hypertension in a randomized, cross-over feeding study of the DASH diet and a control diet. Participants will enter a 2- week run-in period on the control diet followed by two 6-week feeding periods eating the control diet or the DASH diet in random order. After each feeding period, conduit vessel hemodynamic measurements, diastolic relaxation and renal and vascular responses to Ang II will be measured before and after captopril administration. Findings from these studies will determine if the DASH diet favorably affects mechanisms that are altered by the hypertensive process, including renal and cardiac performance, in a group of individuals at higher cardiovascular risk.