Contribution of sympathetic activation to coronary vasodilatation during the cold pressor test in healthy men: effect of ageing
Contribution of sympathetic activation to coronary vasodilatation during the cold pressor test in healthy men: effect of ageing
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DOI：
10.1113/jphysiol.2013.251298
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发表时间：
2013-06-01
影响因子：
5.5
通讯作者：
Gao, Zhaohui
中科院分区：
文献类型：
--
作者：
Monahan, Kevin D.;Feehan, Robert P.;Gao, Zhaohui
关键点中心点交感神经系统是冠状动脉血流量的重要调节器。在生理压力下，衰老如何影响交感神经系统对冠状动脉血流的调节还不清楚。中心点我们测量了年轻和老年健康男性在全身和肾上腺素能受体阻滞之前和期间对交感神经激活的冠状血管反应。我们的研究结果表明，年轻人对交感神经激活的正常冠状血管反应是明显的血管舒张，这种作用随着年龄的增长而消失，这是明显的肾上腺素能机制的结果。这些发现可能有助于解释急性交感神经激活如何引发心绞痛和冠状动脉缺血事件，特别是在老年人中。摘要交感神经系统是冠状动脉血流量的重要调节系统。冷加压试验（CPT）是一种强有力的交感神经兴奋性应激源。我们检验了以下假设：（1）CPT诱导的交感神经激活可增强年轻人的冠状动脉舒张功能，这种功能随着年龄的增长而受损;（2）联合肾上腺素能阻滞可减少/消除这些与年龄相关的差异。在年轻（n = 9; 26 +/-1岁，平均值+/-SEM）和老年健康男性（n = 9; 66 +/-2岁）中，通过经胸多普勒超声心动图在全身性联合给予-和-肾上腺素能拮抗剂之前（阻断前）和期间（阻断后）测定左前降支动脉对CPT的血管反应。冠状动脉血管阻力（CVR;平均动脉压/冠状动脉血流速度）被用作血管张力的指标。CPT降低了年轻人（-33 +/-6%）的CVR（即发生冠状动脉血管舒张），但老年男性（-3 +/-4%; P <0.05 vs.年轻人）在阻滞前没有。肾上腺素能阻滞可消除年轻男性CPT诱导的冠状动脉舒张（阻滞前与阻滞后分别为-33 +/-6% vs. 0 +/-6%; P <0.05），因此阻滞后的反应反映了老年男性的反应（-3 +/-4% vs. 8 +/-9%;与年轻男性阻滞前相比，均P> 0.05）。CPT诱导的冠状血管舒张受损不能用血管舒张刺激减少来解释，因为当CVR反应相对于心肌需氧量（心率-血压乘积）表达时，组和条件效应持续存在。这些数据表明，正常的冠状动脉血管的交感神经激活的年轻男子是显着的血管舒张，这种效果是随着年龄的肾上腺素能机制的结果丢失。这些发现可能有助于解释急性交感神经兴奋如何诱发心绞痛和冠状动脉缺血事件，特别是在老年人中。
Key points center dot The sympathetic nervous system is an important regulator of coronary blood flow. center dot How ageing may effect sympathetic nervous system regulation of coronary blood flow during physiological stress is unknown. center dot We measured coronary vascular responses to sympathetic activation before and during systemic - and -adrenergic receptor blockade in young and older healthy men. center dot Our results indicate that the normal coronary vascular response to sympathetic activation in young men is pronounced vasodilatation and that this effect is lost with advancing age, as the result of an apparent adrenergic mechanism. center dot These findings may help explain how acute sympathetic activation may trigger angina and coronary ischaemic events, particularly in older adults. Abstract The sympathetic nervous system is an important regulator of coronary blood flow. The cold pressor test (CPT) is a powerful sympathoexcitatory stressor. We tested the hypotheses that: (1) CPT-induced sympathetic activation elicits coronary vasodilatation in young adults that is impaired with advancing age and (2) combined - and -adrenergic blockade diminishes/abolishes these age-related differences. Vascular responses of the left anterior descending artery to the CPT were determined by transthoracic Doppler echocardiography before (pre-blockade) and during (post-blockade) systemic co-administration of - and -adrenergic antagonists in young (n= 9; 26 +/- 1 years old, mean +/- SEM) and older healthy men (n= 9; 66 +/- 2 years old). Coronary vascular resistance (CVR; mean arterial pressure/coronary blood velocity) was used as an index of vascular tone. CPT decreased CVR (i.e. coronary vasodilatation occurred) in young (-33 +/- 6%), but not older men (-3 +/- 4%; P < 0.05 vs. young) pre-blockade. Adrenergic blockade abolished CPT-induced coronary vasodilatation in young men (-33 +/- 6%vs. 0 +/- 6%, pre-blockade vs. post-blockade, respectively; P < 0.05) such that responses post-blockade mirrored those of older men (-3 +/- 4%vs. 8 +/- 9%; both P > 0.05 compared to young pre-blockade). Impaired CPT-induced coronary vasodilatation could not be explained by a reduced stimulus for vasodilatation as group and condition effects persisted when CVR responses were expressed relative to myocardial oxygen demand (rate-pressure product). These data indicate that the normal coronary vascular response to sympathetic activation in young men is pronounced vasodilatation and this effect is lost with age as the result of an adrenergic mechanism. These findings may help explain how acute sympathoexcitation may precipitate angina and coronary ischaemic events, particularly in older adults.