The nadir pressure responses to cardiac cycles absent of muscle sympathetic nerve activity (MSNA) bursts (or non-bursts) are typically reported in studies quantifying sympathetic transduction, but the information gained by studying non-bursts is unclear. We tested the hypothesis that longer sequences of non-bursts (≥8 cardiac cycles) would be associated with a greater nadir diastolic blood pressure (DBP) and that better popliteal artery function would be associated with an augmented reduction in DBP. Resting beat-by-beat DBP (via finger photoplethysmography) and common peroneal nerve MSNA (via microneurography) were recorded in 39 healthy, adults (age 23.4 ± 5.3 years; 19 females). For each cardiac cycle absent of MSNA bursts, the mean nadir DBP (ΔDBP) during the 12 cardiac cycles following were determined, and separate analyses were conducted for ≥8 or < 8 cardiac cycle sequences. Popliteal artery endothelial-dependent (via flow-mediated dilation; FMD) and endothelial-independent vasodilation (via nitroglycerin-mediated dilation; NMD) were determined. The nadir DBP responses to sequences ≥8 cardiac cycles were larger (−1.40 ± 1.27 mmHg) than sequences <8 (−0.38 ± 0.46 mmHg; < 0.001). In adjusting for sex and burst frequency (14 ± 8 bursts/min), larger absolute or relative FMD ( < 0.01), but not NMD ( > 0.53) was associated with an augmented nadir DBP. This overall DBP-FMD relationship was similar in sequences ≥8 ( = 0.04–0.05), but not <8 ( > 0.72). The DBP responses to non-bursts, particularly longer sequences, were inversely associated with popliteal endothelial function, but not vascular smooth muscle sensitivity. This study provides insight into the information gained by quantifying the DBP responses to cardiac cycles absent of MSNA.

中文翻译：

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对没有交感神经爆发的较长连续心动周期序列的最低血压反应与腘内皮依赖性扩张相关


在量化交感神经传导的研究中，通常会报告没有肌肉交感神经活动 (MSNA) 爆发（或非爆发）的心动周期的最低压力反应，但通过研究非爆发获得的信息尚不清楚。我们测试了以下假设：较长的非爆发序列（≥8 个心动周期）与较高的最低舒张压 (DBP) 相关，并且更好的腘动脉功能与 DBP 的大幅降低相关。记录了 39 名健康成人（年龄 23.4 ± 5.3 岁；19 名女性）的静息心率 DBP（通过手指光电体积描记法）和腓总神经 MSNA（通过显微神经造影）。对于没有 MSNA 突发的每个心动周期，确定随后 12 个心动周期期间的平均最低 DBP (ΔDBP)，并对≥8 或 < 8 个心动周期序列进行单独分析。确定腘动脉内皮依赖性血管舒张（通过血流介导的扩张；FMD）和内皮非依赖性血管舒张（通过硝酸甘油介导的扩张；NMD）。对序列 ≥8 个心动周期的最低 DBP 响应比序列 <8 id=0> 0.53 更大（-1.40 ± 1.27 mmHg），与最低 DBP 增强相关。这种总体 DBP-FMD 关系在序列 ≥8 (= 0.04–0.05) 中相似，但在 <8 id=1> 0.72 中则不同。 DBP 对非爆发的反应，特别是较长的序列，与腘内皮功能呈负相关，但与血管平滑肌敏感性无关。这项研究通过量化 DBP 对不存在 MSNA 的心动周期的反应来深入了解所获得的信息。