Grassi Guido, Seravalle Gino, Bolla GianBattista, Quarti-Trevano Fosca, Dell'Oro Raffaella, Arenare Francesca, Mancia Giuseppe
Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Università Milano-Bicocca, Ospedale San Gerardo, Monza, Milan, Italy.
J Hypertens. 2008 Jan;26(1):70-5. doi: 10.1097/HJH.0b013e3282f112e6.
Previous studies have shown that heart rate has a limited value in reflecting the chronic state of adrenergic overdrive characterizing several cardiovascular diseases. Whether this also applies to the ability of heart rate to reflect acute and generalized changes in sympathetic activity is unknown.
In 20 healthy young subjects (age: 25.2 +/- 1.2 years, mean +/- SEM) we measured beat-to-beat blood pressure (Finapres), heart rate (HR, ECG), venous plasma norepinephrine (NE, high-performance liquid chromatography) and efferent postganglionic muscle sympathetic nerve traffic (MSNA, microneurography) at rest and during a cold pressor test and two intravenous infusions of nitroprusside at increasing doses.
Both cold pressor test and nitroprusside infusions triggered marked and significant increases in HR, plasma NE and MSNA; blood pressure showing an increase with cold pressor test and a reduction with nitroprusside. The magnitude of the responses was greater with the higher than with the lower dose of nitroprusside. The HR changes induced by cold pressor test were not significantly related to the concomitant NE and MSNA changes (r = -0.08 and r = -0.18, P = NS). This was also the case for the lower and the higher dose of nitroprusside (NE: r = -0.11 and r = 0.08; MSNA: r = 0.01 and r = -0.11, P = NS for all). In contrast NE and MSNA changes induced by cold pressor test and by the lower and the higher dose of nitroprusside were significantly related to each other (r = 0.70, r = 0.89 and r = 0.79 respectively, P < 0.01 for all).
In a given individual, HR responses to sympathetic challenge do not quantitatively reflect the degree of acute and generalized adrenergic activation. Qualitative information on the acute adrenergic effects of given stimuli should thus be based on the assessment of NE and MSNA rather than on HR changes.
既往研究表明，心率在反映几种心血管疾病所特有的肾上腺素能过度激活的慢性状态方面价值有限。心率反映交感神经活动急性和全身性变化的能力是否也如此尚不清楚。
在20名健康年轻受试者（年龄：25.2±1.2岁，均值±标准误）中，我们测量了静息状态下、冷加压试验期间以及两次递增剂量静脉输注硝普钠期间的逐搏血压（Finapres）、心率（HR，心电图）、静脉血浆去甲肾上腺素（NE，高效液相色谱法）和节后肌肉交感神经传出活动（MSNA，微神经ography）。
冷加压试验和硝普钠输注均引发HR、血浆NE和MSNA显著明显升高；血压在冷加压试验时升高，在硝普钠输注时降低。硝普钠高剂量组的反应幅度大于低剂量组。冷加压试验引起的HR变化与同时发生的NE和MSNA变化无显著相关性（r = -0.08和r = -0.18，P = 无显著性差异）。硝普钠低剂量组和高剂量组的情况也是如此（NE：r = -0.11和r = 0.08；MSNA：r = 0.01和r = -0.11，均P = 无显著性差异）。相比之下，冷加压试验以及硝普钠低剂量组和高剂量组引起的NE和MSNA变化彼此显著相关（分别为r = 0.70、r = 0.89和r = 0.79，均P < 0.01）。
在特定个体中，HR对交感神经刺激的反应不能定量反映急性和全身性肾上腺素能激活的程度。因此，关于特定刺激的急性肾上腺素能效应的定性信息应基于对NE和MSNA的评估，而非HR变化。
