Background

Heart rate variability (HRV) is determined by intrinsic sinoatrial node (SAN) activity and the autonomic nervous system (ANS). HRV is reduced in aging; however, aging is heterogeneous. Frailty, which can be measured using a frailty index (FI), can quantify health status in aging separately from chronological age.

Objective

The purpose of this study was to investigate the impacts of age and frailty on HRV in mice.

Methods

Frailty was measured in aging mice between 10 and 130 weeks of age. HRV was assessed using time domain, frequency domain, and Poincaré plot analyses in anesthetized mice at baseline and after ANS blockade, as well as in isolated atrial preparations.

Results

HRV was reduced in aged mice (90–130 weeks and 50–80 weeks old) compared to younger mice (10–30 weeks old); however, there was substantial variability within age groups. In contrast, HRV was strongly correlated with FI score regardless of chronological age. ANS blockade resulted in reductions in heart rate that were largest in 90- to 130-week-old mice and were correlated with FI score. HRV after ANS blockade or in isolated atrial preparations was increased in aged mice but again showed high variability among age groups. HRV was correlated with FI score after ANS blockade and in isolated atrial preparations.

Conclusion

HRV is reduced in aging mice in association with a shift in sympathovagal balance and increased intrinsic SAN beating variability; however, HRV is highly variable within age groups. HRV was strongly correlated with frailty, which was able to detect differences in HRV separately from chronological age.

中文翻译：

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衰弱对衰老小鼠心率变异性的影响：自主神经系统和窦房结的作用

背景

心率变异性 (HRV) 由内在窦房结 (SAN) 活动和自主神经系统 (ANS) 决定。HRV随着年龄的增长而降低；然而，老龄化是异质的。虚弱可以使用虚弱指数 (FI) 来衡量，它可以将衰老中的健康状况与实际年龄分开量化。

客观的

本研究的目的是调查年龄和虚弱对小鼠 HRV 的影响。

方法

在 10 至 130 周龄的老化小鼠中测量了虚弱程度。HRV 使用时域、频域和 Poincaré 图分析在麻醉小鼠的基线和 ANS 阻断后以及孤立的心房准备中进行评估。

结果

与年轻小鼠（10-30 周龄）相比，老年小鼠（90-130 周龄和 50-80 周龄）的 HRV 降低；然而，年龄组之间存在很大差异。相比之下，无论实际年龄如何，HRV 都与 FI 评分密切相关。ANS 阻滞导致 90 至 130 周龄小鼠的心率降低幅度最大，并且与 FI 评分相关。在 ANS 阻断后或在孤立的心房制剂中，老年小鼠的 HRV 增加，但在年龄组之间再次表现出高度的变异性。在 ANS 阻断后和孤立的心房准备中，HRV 与 FI 评分相关。

结论

衰老小鼠的 HRV 降低与交感迷走神经平衡的变化和内在的 SAN 跳动变异性增加有关；然而，HRV 在年龄组内变化很大。HRV 与虚弱密切相关，它能够检测 HRV 与实际年龄的差异。