Oosting J, Struijker-Boudier H A, Janssen B J
Department of Pharmacology, Cardiovascular Research Institute Maastricht, Universiteit Maastricht, The Netherlands.
Am J Physiol. 1997 Jul;273(1 Pt 2):H66-75. doi: 10.1152/ajpheart.1997.273.1.H66.
The aim of the study was to test whether circadian and ultradian variations of cardiac output (CO) in spontaneously hypertensive rats (SHR) differ from those in normotensive Wistar-Kyoto rats (WKY). Twenty-four-hour beat-to-beat recordings of CO (by electromagnetic flow probe) and mean arterial pressure (MAP) were performed in the absence and presence of cardiac autonomic blockade with metoprolol and atropine methylnitrate. Ultradian variability was analyzed by spectral analysis on beat-to-beat data series (high-frequency range) and on averaged minute-to-minute data series (low-frequency range). In general, circadian and ultradian rhythms of CO were similar in SHR (n = 10) and WKY (n = 9). Values of CO were high during the dark and low during the light period, whereas total peripheral resistance was highest during the light period. During cardiac autonomic blockade, relative differences between averaged values of CO over the dark and light periods were reduced. High-frequency spectral power of CO was mainly confined to fluctuations related to respiration and was not influenced by cardiac autonomic blockade. At low-frequency ranges, power spectra of CO lacked a dominant oscillator but showed 1/f characteristics. During cardiac autonomic blockade, low-frequency spectral power of CO fell without changing the 1/f characteristics. These findings suggest that dynamic control of CO is not altered in SHR and that autonomic effects on CO are frequency dependent. In most frequency ranges, the relative variation of CO was higher than that of MAP. Thus, over 24 h in both adult SHR and WKY, MAP is controlled within a more narrow range than CO.
本研究的目的是测试自发性高血压大鼠（SHR）的心输出量（CO）的昼夜节律和超日节律是否与正常血压的Wistar-Kyoto大鼠（WKY）不同。在使用美托洛尔和硝酸甲基阿托品进行心脏自主神经阻滞的情况下和未进行阻滞时，通过电磁流量探头对CO和平均动脉压（MAP）进行24小时逐搏记录。通过对逐搏数据序列（高频范围）和平均每分钟数据序列（低频范围）进行频谱分析来分析超日变异性。总体而言，SHR（n = 10）和WKY（n = 9）的CO昼夜节律和超日节律相似。CO值在黑暗期较高，在光照期较低，而总外周阻力在光照期最高。在心脏自主神经阻滞后，黑暗期和光照期CO平均值之间的相对差异减小。CO的高频频谱功率主要局限于与呼吸相关的波动，不受心脏自主神经阻滞的影响。在低频范围内，CO的功率谱缺乏主导振荡器，但呈现1/f特征。在心脏自主神经阻滞后，CO的低频频谱功率下降，但1/f特征不变。这些发现表明，SHR中CO的动态控制没有改变，并且自主神经对CO的影响是频率依赖性的。在大多数频率范围内，CO的相对变化高于MAP。因此，在成年SHR和WKY中，24小时内MAP的控制范围比CO更窄。
