AGE, EXERCISE, THERMOGENESIS AND POSTPRANDIAL HYPOTENSIO

年龄、运动、产热和餐后低血压

• 批准号: 6349730
• 负责人: DOUGLAS R SEALS
• 金额: $ 26.53万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6349730
• 关键词: adipose tissue; age difference; aging; baroreflex; basal metabolism; bioenergetics; blood pressure; clinical research; eating; exercise; heart rate; human middle age (35-64); human old age (65+); human subject; hyperinsulinism; hypotension; nutrition related tag; obesity; sympathetic nervous system; tachycardia; thermogenesis; vagus nerve; vasoconstriction; young adult human (21-34)

In young adult humans, acute energy intake (feeding) evokes an integrative "postprandial" physiological response which includes an increase in metabolic rate (thermic effect of food intake--TEF) and a number of autonomic nervous system (ANS) and cardiovascular adjustments aimed at providing increased blood flow for digestion (splanchnic vasodilation) while maintaining arterial blood pressure (BP) at preprandial levels. Some older adults with chronic diseases demonstrate a reduced TEF and/or a postprandial fall in BP ("postprandial hypotension"), but it is unknown whether this occurs with age in healthy adults. If the latter is true, some evidence suggests that these changes may not occur with age in adult humans who exercise regularly. The specific aims of the present proposal are to determine if: (1) TEF is lower and postprandial BP declines occur in middle-aged and/or older sedentary adults compared with young adult controls; (2) the lower TEF is due to attenuated postprandial increases in sympathetic nervous system (SNS) activity associated with reduced CNS sympathoexcitatory responsiveness to acute hyperinsulinemia; (3) the postprandial hypotension also is associated with: a) an attenuated or absent whole-limb and skeletal muscle vasoconstriction; b) a smaller reduction in cardiac vagal modulation of heart rate and an attenuated tachycardia; and c) a lower baseline cardiac vagal tone and arterial baroreflex sensitivity; (4) middle-aged and older adults who exercise regularly do not demonstrate the lower TEF and postprandial hypotension observed with age in sedentary humans, and whether this is associated with augmented SNS responses, CNS sympathetic responsiveness to circulating insulin, limb vasoconstriction, vagally-mediated tachycardia, baseline cardiac vagal tone and baroreflex sensitivity; and (5) the reduced TEF and postprandial hypotension associated with sedentary aging are related to elevated adiposity. Because TEF contributes significantly to daily energy expenditure and, therefore, energy balance, the expected results should provide new and clinically important information concerning the effects of sedentary aging, regular exercise and adiposity on TEF in the context of age-related obesity and its metabolic and cardiovascular co-morbidities. Moreover, postprandial hypotension is associated with post-meal dizziness, weakness, syncope, cerebrovascular ischemia, and angina pectoris. As such, the expected results should provide new insight into the effects of sedentary aging, habitual exercise and body fatness on this clinically-important cardiovascular disorder.

在年轻的成年人中，急性能量摄入（进食）引起综合的“餐后”生理反应，其包括代谢率的增加（食物摄入的热效应-TEF）和许多自主神经系统（ANS）和心血管调节，旨在提供用于消化的增加的血流（内脏血管舒张），同时将动脉血压（BP）维持在餐前水平。 一些患有慢性疾病的老年人表现出TEF降低和/或餐后血压下降（“餐后低血压”），但尚不清楚这是否会随着健康成人的年龄而发生。 如果后者是真的，一些证据表明，这些变化可能不会随着年龄的增长而发生在经常锻炼的成年人身上。 本提案的具体目的是确定：（1）与年轻成人对照组相比，中年和/或老年久坐成人的TEF较低，餐后血压下降;（2）TEF较低是由于餐后交感神经系统（SNS）活性增加减弱，与CNS对急性高胰岛素血症的交感神经兴奋反应性降低有关;（3）餐后低血压还与以下有关：a）减弱或不存在全肢和骨骼肌血管收缩; B）心率的心脏迷走神经调节的较小降低和减弱的心动过速;和c）较低的基线心脏迷走神经张力和动脉压力反射敏感性;（4）经常锻炼的中老年人没有表现出较低的TEF和餐后低血压，以及这是否与SNS反应增强、CNS交感神经对循环胰岛素的反应、肢体血管收缩、迷走神经介导的心动过速、基线心脏迷走神经张力和压力反射敏感性有关;（5）与久坐老化相关的TEF降低和餐后低血压与肥胖增加有关。 由于TEF对每日能量消耗和能量平衡有显著贡献，因此预期结果应提供关于久坐老化、定期运动和肥胖在年龄相关性肥胖及其代谢和心血管共病背景下对TEF影响的新的临床重要信息。此外，餐后低血压与餐后头晕、虚弱、晕厥、脑血管缺血和心绞痛有关。 因此，预期的结果应该为久坐不动的衰老，习惯性运动和身体肥胖对这种临床重要的心血管疾病的影响提供新的见解。