SYMPATHETIC NERVOUS SYSTEM INFLUENCE ON BLOOD PRESSURE REGULATION W/AGE

动脉血压(BP)对人体生理稳态有重要影响，血压调节异常具有潜在的病理生理后果。自主神经系统(ANS)是BP心血管决定因素的关键调节因子。ANS对动脉血压的支持可能存在与年龄相关的变化，这可能至少部分与肾上腺素能受体敏感性的差异有关。本研究的主要目的是验证以下假设：1)基础ANS音调对维持健康成年人的静息血压及其循环决定因素有显著贡献；2)ANS对BP的支持随着初级(健康)年龄的增长而增加；以及3)肾上腺素能受体敏感性随着初级年龄的增长而降低。为了验证这些假说，我们正在使用自主神经节拮抗剂曲美沙潘来消除心血管组织中的ANS输入，从而量化其对维持BP的贡献。在测量心率、血压和小腿血流时，注入肾上腺素能激动剂苯肾上腺素(a-激动剂)和异丙肾上腺素(b-激动剂)，以确定肾上腺素能受体的敏感性(即效应组织对肾上腺素能刺激的反应性)。正在对两组健康受试者进行研究：27名健康青年(50%女性)和27名老年健康成年人(50%女性)。

Arterial blood pressure (BP) exerts a critical influence on physiological homeostasis in humans, and abnormalities in BP regulation have potential pathophysiological consequences. The autonomic nervous system (ANS) is a key regulator of the cardiovascular determinants of BP. There may be age-related changes in ANS support of arterial blood pressure, and these may be at least partially related to differences in adrenergic receptor sensitivity. The general aims of this study are to test the hypotheses that: 1) basal ANS tone makes a significant contribution to the maintenance of resting BP and its circulatory determinants in the healthy adult human; 2) ANS support of BP is increased with primary (healthy) aging; and 3) adrenergic receptor sensitivity is reduced with primary aging. To test these hypotheses we are using the autonomic ganglionic antagonist, Trimethaphan, to eliminate ANS input to cardiovascular tissues, and thereby quantify its contribution to the maintenance of BP. The adrenergic agonists phenylephrine (a-agonist), and isoproterenol (b-agonist) are infused during measurements of heart rate, BP, and calf blood flow, to determine adrenergic receptor sensitivity (i.e., effector tissue responsiveness to adrenergic stimuli). Two groups of healthy subjects are being studied: 27 young healthy (50% female), and 27 older healthy (50% female) adults.