Aging and cardiovascular responsiveness to beta-agonist in humans: role of changes in beta-receptor responses versus baroreflex activity.
Aging and cardiovascular responsiveness to beta-agonist in humans: role of changes in beta-receptor responses versus baroreflex activity.
复制标题
人类衰老和心血管对 β 激动剂的反应：β 受体反应变化与压力反射活动的作用。
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
F. Leenen
中科院分区：
文献类型：
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作者：
M. White;F. Leenen
目标
评估心脏变时性和变力性反应以及动脉对β受体刺激的反应的年龄相关变化，以及动脉压力感受性反射对这些反应的潜在作用。
方法和结果
在14名年轻受试者（年龄，30 +/- 2岁）和15名老年健康志愿者（年龄，60 +/- 2岁）中单独输注异丙肾上腺素，并在8名年轻受试者和8名老年受试者中与神经节阻滞剂（曲美沙芬）一起输注。异丙肾上腺素以3 - 4个递增速率输注。通过超声心动图评估心脏功能，通过静脉闭塞体积描记术测量外周动脉反应。在神经节阻滞前，异丙肾上腺素以0.005 - 0.03 μ g/kg/min的输注速率在年轻和老年受试者中引起心率、射血分数和平均标准化收缩期射血率的相似变化。伴随使用曲美沙芬，异丙肾上腺素以0.0025 - 0.01 μ g/kg/min的输注速率在年轻受试者中引起心率更大幅度的增加（输注峰值时29 +/- 2次/分钟[年轻人] vs 20 +/- 3 [老年人]; p = 0.03），射血分数（11% +/- 2% [年轻人]对6% +/- 1% [老年人]; p < 0.01）和平均标准化收缩期射血率（1.13 +/- 0.2 ml/sec [年轻人]对0.48 +/- 0.09 [老年人]; p < 0.01）。而总外周阻力的百分比变化较大的年轻受试者，有没有显着的年龄相关的差异，前臂血流和阻力的反应之前或之后神经节阻滞。
结论
这些结果表明，年龄相关的降低β受体反应性的窦房结和心室肌，这是掩盖了伴随减少压力反射控制的心脏。
OBJECTIVES
To assess age-related changes in the cardiac chronotropic and inotropic responses and arterial responses to beta-receptor stimulation and the potential role of the arterial baroreflex on these responses.
METHODS AND RESULTS
Isoproterenol alone was infused in 14 young subjects (age, 30 +/- 2 years) and 15 older healthy volunteers (age, 60 +/- 2 years) and together with ganglionic blockade (trimethaphan) in eight young and eight older subjects. Isoproterenol was infused at 3 to 4 incremental rates. Cardiac function was assessed by echocardiography and peripheral arterial responses were measured by venous occlusion plethysmography. Before ganglionic blockade, isoproterenol at infusion rates from 0.005 to 0.03 micrograms/kg/min caused similar changes in heart rate, ejection fraction, and mean normalized systolic ejection rate in the young and older subjects. With concomitant use of trimethaphan, isoproterenol at infusion rates from 0.0025 to 0.01 micrograms/kg/min caused in young subjects a larger increase in heart rate (29 +/- 2 beats/min [young] versus 20 +/- 3 [older] at peak infusion; p = 0.03), ejection fraction (11% +/- 2% [young] versus 6% +/- 1% [older]; p < 0.01), and mean normalized systolic ejection rate (1.13 +/- 0.2 ml/sec [young] versus 0.48 +/- 0.09 [older]; p < 0.01). Whereas percentage changes in total peripheral resistance were larger in the young subjects, there were no significant age-related differences in the responses of forearm blood flow and resistance before or after ganglionic blockade.
CONCLUSIONS
These results indicate an age-related decrease in beta-receptor responsiveness of both sinoatrial node and ventricular myocardium that is masked by a concomitant decrease in the baroreflex control of the heart.