Decreased maximal heart rate with aging is related to reduced β-adrenergic responsiveness but is largely explained by a reduction in intrinsic heart rate
Decreased maximal heart rate with aging is related to reduced β-adrenergic responsiveness but is largely explained by a reduction in intrinsic heart rate
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DOI：
10.1152/japplphysiol.90401.2008
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发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Seals, Douglas R.
中科院分区：
文献类型：
--
作者：
Christou, Demetra D.;Seals, Douglas R.
最大运动心率(HRmax)的下降是随着年龄的增长有氧运动能力下降的关键因素。然而，所涉及的机制还不完全清楚。我们试图深入了解内在心率(HRINT)和变时性β-肾上腺素能反应在健康成年人HRmax随年龄增长而降低中的各自作用。对15例老年(65+/-5岁)和15例青年(25+/-4岁)健康男性进行了心率最大耗竭试验(Balke平板运动至力竭)、心率试验(静脉注射曲美沙芬急性神经节阻滞时的心率)和变时性β-肾上腺素能反应(节段性阻滞时静脉滴注异丙肾上腺素使心率增加)。老年男性HRmax较低(16 2+/-9次/分钟比191+/-11次/分钟，P<；0.0001)，并与较低的HRint(58+/-7次/分钟比83+/-9次/分钟，P<；0.0001)和变时性β-肾上腺素能反应性(0.094+/-0.036次比0.154+/-0.045增量HR/[异丙肾上腺素]：P<；0.0001)有关。心率间期(r=0.87P<；0.0001)和变时性β-肾上腺素能反应性(r=0.61P<；0.0001)均与心率最大值呈正相关。考虑到HRint和变时性β-肾上腺素能反应的影响，与年龄相关的HRmax差异减少了83%，使其在统计学上无统计学意义(P=0.2)。老年男性最大耗氧量低于老年男性(48.6±6.7ml.kg(-1).min(-1)，P<；0.0001)，并与心率最大值(r=0.62，P<0.0001)、心率积分(r=0.51，P=0.002)、变时性β-肾上腺素能反应性(r=0.47，P=0.005)呈正相关。我们的发现表明，HRint的降低和对β-肾上腺素能刺激的变时性反应在很大程度上解释了HRmax随年龄增长而降低的原因，其中HRint的降低起到了最大的作用。
A decrease in maximal exercise heart rate (HRmax) is a key contributor to reductions in aerobic exercise capacity with aging. However, the mechanisms involved are incompletely understood. We sought to gain insight into the respective roles of intrinsic heart rate (HRint) and chronotropic beta-adrenergic responsiveness in the reductions in HRmax with aging in healthy adults. HRmax (Balke treadmill protocol to exhaustion), HRint (HR during acute ganglionic blockade with intravenous trimethaphan), and chronotropic beta-adrenergic responsiveness (increase in HR with incremental intravenous infusion of isoproterenol during ganglionic blockade) were determined in 15 older (65 +/-5 yr) and 15 young (25 +/-4 yr) healthy men. In the older men, HRmax was lower (162 +/-9 vs. 191 +/-11 beats/ min, P < 0.0001) and was associated with a lower HRint (58 +/-7 vs. 83 +/-9 beats/ min, P < 0.0001) and chronotropic beta-adrenergic responsiveness (0.094 +/-0.036 vs. 0.154 +/-0.045 Delta HR/[isoproterenol]: P < 0.0001). Both HRint (r = 0.87, P < 0.0001) and chronotropic beta-adrenergic responsiveness (r = 0.61, P < 0.0001) were positively related to HRmax. Accounting for the effects of HRint and chronotropic beta-adrenergic responsiveness reduced the age-related difference in HRmax by 83%, rendering it statistically nonsignificant (P = 0.2). Maximal oxygen consumption was lower in the older men (34.9 +/-8.1 vs. 48.6 +/-6.7 ml.kg(-1).min(-1), P < 0.0001) and was positively related to HRmax (r = 0.62, P < 0.0001), HRint (r = 0.51, P = 0.002), and chronotropic beta-adrenergic responsiveness (r = 0.47, P = 0.005). Our findings indicate that, together, reductions in HRint and chronotropic responsiveness to beta-adrenergic stimulation largely explain decreases in HRmax with aging, with the reduction in HRint playing by far the greatest role.