Dynamic accentuated antagonism of heart rate control during different levels of vagal nerve stimulation intensity in rats
Dynamic accentuated antagonism of heart rate control during different levels of vagal nerve stimulation intensity in rats
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不同迷走神经刺激强度对大鼠心率控制的动态增强拮抗作用
DOI：
10.1152/ajpregu.00229.2022
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Saku Keita
中科院分区：
文献类型：
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作者：
Kawada Toru;Yokoi Aimi;Nishiura Akitsugu;Kakuuchi Midori;Yokota Shohei;Matsushita Hiroki;Li Meihua;Uemura Kazunori;Saku Keita
强调拮抗是指迷走神经对心率(HR)的影响被背景交感神经刺激增强的现象。在不同水平的迷走神经刺激(VNS)中，强烈的拮抗作用的动态方面仍有待阐明。我们对麻醉大鼠(n=8)进行了三种不同刺激频率(低强度：0-10 Hz，中强度：0-20 Hz，高强度：0-40 Hz)下的二进制白噪声信号的VNS。在5 Hz频率下，分别在紧张性交感神经刺激(SNS)和非紧张性交感神经刺激(SNS)的条件下，测定VNS到HR的传递函数。传递函数的低频增益(以次/分/赫兹为单位)随刺激频率的增加而增加[低强度：3.93 ± 0.70vs.5.82 ± 0.65(P=0.021)，中强度：3.87 ± 0.62vs.5.36 ± 0.53(P=0.018)，高强度：4.77 ± 0.85vs.7.39 ± 1.36(P=0.011)]。此外，SNS还略微增加了高频(HF)增益与低频增益的比率。在另一组大鼠(n=6)中，SNS的上述作用可被超极化激活的环核苷酸门控通道的抑制剂伊夫拉定所抵消。虽然背景交感神经张力对抗迷走神经对平均心率的影响，但它通过增加迷走神经HR传递函数的动态增益来实现更精细的心率控制，而不考虑VNS的强度。在解释心率变异性的高频成分时，需要考虑背景交感音的增强效应。
Accentuated antagonism refers to a phenomenon in which the vagal effect on heart rate (HR) is augmented by background sympathetic tone. The dynamic aspect of accentuated antagonism remains to be elucidated during different levels of vagal nerve stimulation (VNS) intensity. We performed VNS on anesthetized rats (n= 8) according to a binary white noise signal with a switching interval of 500 ms at three different stimulation rates (low-intensity: 0–10 Hz, moderate-intensity: 0–20 Hz, and high-intensity: 0–40 Hz). The transfer function from VNS to HR was estimated with and without concomitant tonic sympathetic nerve stimulation (SNS) at 5 Hz. The asymptotic low-frequency (LF) gain (in beats/min/Hz) of the transfer function increased with SNS regardless of the VNS rate [low-intensity: 3.93 ± 0.70 vs. 5.82 ± 0.65 (P= 0.021), moderate-intensity: 3.87 ± 0.62 vs. 5.36 ± 0.53 (P= 0.018), high-intensity: 4.77 ± 0.85 vs. 7.39 ± 1.36 (P= 0.011)]. Moreover, SNS slightly increased the ratio of high-frequency (HF) gain to the LF gain. These effects of SNS were canceled by the pretreatment of ivabradine, an inhibitor of hyperpolarization-activated cyclic nucleotide-gated channels, in another group of rats (n= 6). Although background sympathetic tone antagonizes the vagal effect on mean HR, it enables finer HR control by increasing the dynamic gain of the vagal HR transfer function regardless of VNS intensity. When interpreting the HF component of HR variability, the augmenting effect from background sympathetic tone needs to be considered.