Exercise intensity influences cardiac baroreflex function at the onset of isometric exercise in humans
Exercise intensity influences cardiac baroreflex function at the onset of isometric exercise in humans
复制标题
DOI：
10.1152/japplphysiol.00412.2007
复制
发表时间：
2007-09-01
影响因子：
3.3
通讯作者：
Fadel, Paul J.
中科院分区：
文献类型：
--
作者：
Fisher, James P.;Ogoh, Shigehiko;Fadel, Paul J.
我们试图研究运动强度对颈动脉压力感受性反射（CBR）控制心率（HR）和平均动脉压（MAP）的影响。为了实现这一点，8名受试者进行了多次1分钟的等长握柄（HG）运动在15，30，45和60%的最大自主收缩（MVC），而呼吸的节拍器设置在正常的频率。在呼气末施加-60托的颈部抽吸（NS）5秒，以刺激静息时、HG开始时（< 1秒）和类似于HG 40秒后的CBR。全程记录心率和平均动脉压的逐搏测量值。在15%（-12 +/-2次/分钟）和30%（-10 +/-2次/分钟）MVC HG开始时对NS的心脏反应与静息时（-10 +/-1次/分钟）相似。然而，在45%和60%MVC HG开始时，对NS的HR反应降低（分别为-6 +/-2和-4 +/-1次/分钟; P < 0.001）。与HR相反，在运动开始时，对NS的MAP反应与休息时没有差异。此外，HR和MAP对NS的反应在类似于40 s的HG时与休息时相似。总之，CBR控制的HR在高强度HG的立即发作时短暂钝化，而MAP反应被保留，表明在运动开始时HR和血压的差异压力感受性反射控制。总的来说，这些结果表明，颈动脉-心脏压力反射控制在人体等长运动中动态调节，而颈动脉压力反射对血压的调节维持良好。
We sought to examine the influence of exercise intensity on carotid baroreflex (CBR) control of heart rate (HR) and mean arterial pressure (MAP) at the onset of exercise in humans. To accomplish this, eight subjects performed multiple 1-min bouts of isometric handgrip (HG) exercise at 15, 30, 45 and 60% maximal voluntary contraction (MVC), while breathing to a metronome set at eupneic frequency. Neck suction (NS) of -60 Torr was applied for 5 s at end expiration to stimulate the CBR at rest, at the onset of HG (< 1 s), and after similar to 40 s of HG. Beat-to-beat measurements of HR and MAP were recorded throughout. Cardiac responses to NS at onset of 15% (-12 +/- 2 beats/min) and 30% (-10 +/- 2 beats/min) MVC HG were similar to rest (-10 +/- 1 beats/min). However, HR responses to NS were reduced at the onset of 45% and 60% MVC HG (-6 +/- 2 and -4 +/- 1 beats/min, respectively; P < 0.001). In contrast to HR, MAP responses to NS were not different from rest at exercise onset. Furthermore, both HR and MAP responses to NS applied at similar to 40s of HG were similar to rest. In summary, CBR control of HR was transiently blunted at the immediate onset of high-intensity HG, whereas MAP responses were preserved demonstrating differential baroreflex control of HR and blood pressure at exercise onset. Collectively, these results suggest that carotid-cardiac baroreflex control is dynamically modulated throughout isometric exercise in humans, whereas carotid baroreflex regulation of blood pressure is well-maintained.