Sano H, Hayashi H, Makino M, Takezawa H, Hirai M, Saito H, Ebihara S
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Jpn Circ J. 1995 Aug;59(8):565-73. doi: 10.1253/jcj.59.565.
To determine whether the circadian rhythms in blood pressure (BP), heart rate (HR) and locomotor activity are controlled by an internal biological clock located in the suprachiasmatic nucleus (SCN), we continuously measured these parameters in SCN-lesioned rats using a newly developed implantable radiotelemetry device and a computerized data collecting system. Although SCN-lesioned rats showed a weak but significant 24-h periodicity in BP and HR under light-dark (LD) cycles, BP, HR and locomotor activity became completely aperiodic under constant dark (DD) conditions. The amount of locomotor activity was significantly reduced in SCN-lesioned rats compared to that in intact rats. BP tended to be higher in SCN-lesioned rats, but the differences were significant only in the comparison of systolic blood pressure (SBP) under LD and DD (p < 0.05) and of mean blood pressure (MBP) under LD (p < 0.05). HR in SCN-lesioned rats was significantly lower under LD (p < 0.05), but not under DD. The standard deviation and the variation coefficient of MBP, as indices of short-term variability of this parameter, were significantly larger in SCN-lesioned rats than in intact rats, while those of HR and locomotor activity did not differ significantly between SCN-lesioned and intact rats. These results indicate that the SCN is important not only for generating circadian rhythms of BP, HR and locomotor activity, but also for buffering the short-term variability of BP in rats.
为了确定血压（BP）、心率（HR）和运动活动的昼夜节律是否由位于视交叉上核（SCN）的内部生物钟控制，我们使用新开发的植入式无线电遥测设备和计算机化数据收集系统，连续测量了SCN损伤大鼠的这些参数。尽管SCN损伤大鼠在明暗（LD）循环下BP和HR显示出微弱但显著的24小时周期性，但在持续黑暗（DD）条件下，BP、HR和运动活动完全变为无周期性。与完整大鼠相比，SCN损伤大鼠的运动活动量显著减少。SCN损伤大鼠的BP往往较高，但差异仅在LD和DD下收缩压（SBP）的比较中显著（p<0.05）以及LD下平均血压（MBP）的比较中显著（p<0.05）。SCN损伤大鼠的HR在LD下显著较低（p<0.05），但在DD下不显著。作为该参数短期变异性指标的MBP的标准差和变异系数，在SCN损伤大鼠中显著大于完整大鼠，而HR和运动活动的标准差和变异系数在SCN损伤大鼠和完整大鼠之间无显著差异。这些结果表明，SCN不仅对产生BP、HR和运动活动的昼夜节律很重要，而且对缓冲大鼠BP的短期变异性也很重要。
