Racial Differences--Stress Induced Homeostatic Response

这项研究的总体目标是更全面地了解应激引起的生理变化在原发性高血压的种族差异发展中所起的作用。对压力的生理反应是一个动态的过程。它包括对应激源本身的反应和使身体进入动态平衡的生理反应。绝大多数的研究都集中在应激时的生理反应上，而在很大程度上忽视了应激后体内平衡的变化。关于群体差异的信息很少。这一建议的一般假设如下：与高加索人相比，非裔美国人在压力期间和之后表现出较慢的钠尿，并伴随着更大的血管收缩。这将导致应激后较长时间的血压升高，使这些人暴露在血压负荷增加的情况下，这会导致终末器官变化的过早发展。因此，本研究的目的是：1)对比非裔美国人和高加索受试者在60分钟应激前、应激期间和应激后2小时的血流动力学调节；2)对比非裔美国人和高加索受试者在应激过程中的激素调节；3)对比非裔美国人和高加索受试者在应激过程中对Na+的处理水平；4)确定靶器官变化指标与恢复期血压变化之间的关系。这项拟议的研究将通过a)首次确定与反应相关的激素机制；以及b)通过将反应与靶器官的变化联系起来，首次确定反应的临床意义，从而极大地增加对受损的体内平衡过程的潜在因素和重要性的最低限度的了解。

The overall goal of this study is to obtain a more complete understanding of the role that physiologic changes induced by stress play in the development of ethnic differences in essential hypertension. The physiologic response to stress is a dynamic process. It includes the response to the stressor per se AND the physiologic response, which bring the body into homeostasis. The vast majority of research has focused on the physiologic response during stress while homeostatic changes following stress have largely been ignored. There is very little information about group differences. The general hypothesis of this proposal is as follows: African-Americans compared to Caucasians show slower natriuresis during and following the stress coupled with greater vasoconstriction. This will result in an extended period of elevated blood pressure following stress, exposing these individuals to an increased BP load, which leads to the premature development of end organ changes. Therefore, the aims of this study are: 1) contrast hemodynamic regulation in African-American and Caucasian subjects before, during, and two hours following a 60 minute stress period; 2) contrast hormonal regulation in African-American and Caucasian subjects during the procedure; 3) contrast levels of Na+ handling between African-American and Caucasian subjects during the procedure; 4) determine the relationship between measures of target organ change and BP changes during the recovery period. The proposed study will add considerably to the minimal knowledge of the factors underlying, and significance of, an impaired homeostatic process by a) for the first time identifying hormonal mechanism associated with the response; and b) for the first time determining the clinical significance of the response by relating it to target organ changes.