Sayin Halil, Chapuis Bruno, Chevalier Philippe, Barrès Christian, Julien Claude
Neurocardiology Unit, Medical School Lyon East, University Claude Bernard Lyon 1, Lyon, France.
Neurocardiology Unit, Medical School Lyon East, University Claude Bernard Lyon 1, Lyon, France.
Auton Neurosci. 2016 Jan;194:26-31. doi: 10.1016/j.autneu.2015.12.007. Epub 2015 Dec 29.
Cardiac autonomic tone can be assessed either by estimating separately vagal and sympathetic tones or by evaluating the net effect of their interaction, the so-called sympathovagal balance (SVB). To compare the most commonly used methods in rats, telemetric recordings of the electrocardiogram were performed in normotensive WKY rats, and in groups of spontaneously hypertensive (SHR) rats that were either untreated or chronically treated with the cholinesterase inhibitor, pyridostigmine, to enhance vagal tone. Cardiac autonomic blockers were administered alone and in combination, so that heart rate (HR) could be measured (1) under resting conditions, (2) with either autonomic branch blocked, and (3) with both branches blocked (which provided intrinsic HR, iHR). SVB was assessed as the ratio of resting HR to iHR. This calculation pointed to a sympathetic predominance in untreated SHRs and even more so in WKY rats, and to a marked vagal predominance in pyridostigmine-treated SHRs. By contrast, the ratio between low and high frequency components (LF/HF) of RR interval spectra did not significantly differ between the groups. Each autonomic tone was quantified as the HR change induced by its selective blocker or as the difference between iHR and HR after blockade of its counterpart. Both pharmacological methods indicated vagal enhancement in treated SHRs, but provided opposite results in terms of vagal vs. sympathetic predominance. These data seriously question the use of the LF/HF ratio as an index of SVB, and the possibility to reliably estimate vagal and sympathetic tones separately through current pharmacological approaches in conscious rats.
心脏自主神经张力可以通过分别估计迷走神经和交感神经张力来评估，也可以通过评估它们相互作用的净效应，即所谓的交感迷走平衡（SVB）来评估。为了比较大鼠中最常用的方法，对正常血压的WKY大鼠以及未治疗或长期用胆碱酯酶抑制剂吡啶斯的明治疗以增强迷走神经张力的自发性高血压（SHR）大鼠组进行了心电图遥测记录。单独和联合给予心脏自主神经阻滞剂，以便可以测量心率（HR）：（1）在静息状态下，（2）自主神经分支之一被阻断时，以及（3）两个分支都被阻断时（这提供了固有心率，iHR）。SVB被评估为静息HR与iHR的比值。该计算表明，未治疗的SHR中交感神经占优势，WKY大鼠中更是如此，而在吡啶斯的明治疗的SHR中迷走神经明显占优势。相比之下，各组之间RR间期频谱的低频和高频成分之比（LF/HF）没有显著差异。每种自主神经张力通过其选择性阻滞剂引起的HR变化或通过阻断其对应神经后iHR与HR之间的差异来量化。两种药理学方法均表明治疗的SHR中迷走神经增强，但在迷走神经与交感神经占优势方面提供了相反的结果。这些数据严重质疑将LF/HF比值用作SVB指标的用途，以及通过当前药理学方法在清醒大鼠中分别可靠估计迷走神经和交感神经张力的可能性。
