Dynamic blood pressure control and middle cerebral artery mean blood velocity variability at rest and during exercise in humans.
Dynamic blood pressure control and middle cerebral artery mean blood velocity variability at rest and during exercise in humans.
复制标题
动态血压控制和大脑中动脉意味着人类在休息和运动期间的血流速度变异性。
DOI：
10.1111/j.1748-1716.2007.01708.x
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Raven,PB
中科院分区：
文献类型：
--
作者：
Ogoh,S;Dalsgaard,MK;Secher,NH;Raven,PB
目的：心力衰竭和缺血性心脏病患者接受心脏β1-肾上腺素能阻滞药物的标准治疗。这种药物会减少心输出量和脑血流量。尚不清楚在运动诱导的心动脉压力反射增益降低的情况下，β1肾上腺素能阻滞诱导的心输出量降低是否会影响脑血流变异性。本研究评价了运动时心输出量变异性对心搏间大脑中动脉平均血流速度（MCAVmean）的影响，并进行了心脏选择性β1肾上腺素能阻滞（0.15 mg kg − 1美托洛尔）治疗。方法：8名男性（22 ± 1岁;平均值± SE）在心脏选择性β1肾上腺素能阻滞（0.15 mg kg− 1美托洛尔）治疗前后进行了15min的中等强度（105 ± 11 W）和重强度（162 ± 8 W）循环。 结果：两种运动强度均使心输出量与MCAVmean之间的低频（LF）传递函数增益降低（P< 0.05），β1受体阻滞剂对心输出量与MCAVmean之间的低频（LF）传递函数增益无显著影响。 而MAP与MCAV平均值之间的LF传递函数增益保持稳定，美托洛尔对其无显著影响（P> 0.05）。 MAP和HR之间的LF传递函数增益（心脏-动脉压力反射增益的指标）在有和没有β1-受体阻滞剂的情况下从休息到剧烈运动降低（P<0. 05）。结论：这些结果表明，即使心脏β1-肾上腺素能阻滞剂降低了运动诱导心输出量增加的能力，运动强度相关的心脏-动脉压力反射功能在其工作点的降低也不影响MCAV mean的动态控制。
Aims:Cardiac failure and ischaemic heart disease patients receive standard of care cardiacβ1‐adrenergic blockade medication. Such medication reduces cardiac output and cerebral blood flow. It is unknown whether theβ1‐adrenergic blockade‐induced reduction of cardiac output in the presence of an exercise‐induced reduction in cardiac–arterial baroreflex gain affects cerebral blood flow variability. This study evaluated the influence of cardiac output variability on beat‐to‐beat middle cerebral artery mean blood velocity (MCAVmean) during exercise with and without cardiacβ1‐adrenergic blockade.Methods:Eight men (22 ± 1 years; mean ± SE) performed 15 min bouts of moderate (105 ± 11 W) and heavy (162 ± 8 W) intensity cycling before and after cardio‐selectiveβ1‐adrenergic blockade (0.15 mg kg−1metoprolol). The relationship between changes in cardiac output or mean arterial pressure (MAP) and MCAVmeanas well as cardiac–arterial baroreflex gain were evaluated using transfer function analysis.Results:Both exercise intensities decreased the low frequency (LF) transfer function gain between cardiac output and MCAVmean(P< 0.05) with no significant influence ofβ1‐blockade. In contrast, the LF transfer function gain between MAP and MCAVmeanremained stable also with no significant influence of metoprolol (P> 0.05). The LF transfer function gain between MAP and HR, an index of cardiac–arterial baroreflex gain, decreased from rest to heavy exercise with and withoutβ1‐blockade (P< 0.05).Conclusion:These findings suggest that the exercise intensity related reduction in cardiac–arterial baroreflex function at its operating point does not influence the dynamic control of MCAVmean, even when the ability of exercise‐induced increase in cardiac output is reduced by cardiacβ1‐adrenergic blockade.