Friberg P, Karlsson B, Nordlander M
Department of Physiology, University of Gothenburg, Sweden.
J Hypertens. 1989 Oct;7(10):799-807. doi: 10.1097/00004872-198910000-00005.
The relative influences of sympathetic and parasympathetic neural modulation on mean arterial pressure (MAP) and heart rate (HR), and their respective variabilities, were studied in young spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). An on-line computerized system was used for continuous intra-arterial measurements of MAP and HR in unrestrained rats. In addition, the autonomic nervous control of MAP and HR was studied in ageing SHR and WKY. Both WKY and SHR showed diurnal rhythms with regard to MAP and HR. The MAP variability was higher in SHR than in WKY during both daytime (inactive) and night-time (active), and did not change in response to either beta 1-adrenoceptor- or cholinergic blockade. Structural vascular changes, with a resultant increase in reactivity, may explain the elevated MAP variability in SHR. HR variability was clearly reduced in SHR; this was not influenced by vagal blockade, whereas HR variability was significantly reduced in WKY. This pattern is suggested to be due to a reduced tonic vagal discharge in SHR, as part of a persistent, mild defence reaction. The initial reduction in vagal activity will in turn eliminate vagally mediated tachycardias. Furthermore, administration beta 1-blockade to SHR of different ages caused a greater fall in MAP and HR than in WKY, indicating an increased dependence upon the sympathetic nervous system in SHR with age.
在年轻的自发性高血压大鼠（SHR）和Wistar-Kyoto大鼠（WKY）中，研究了交感神经和副交感神经调节对平均动脉压（MAP）和心率（HR）及其各自变异性的相对影响。使用在线计算机系统对未束缚大鼠的MAP和HR进行连续动脉内测量。此外，还研究了衰老的SHR和WKY中MAP和HR的自主神经控制。WKY和SHR在MAP和HR方面均表现出昼夜节律。在白天（不活动）和夜间（活动）期间，SHR的MAP变异性均高于WKY，并且对β1肾上腺素能受体或胆碱能阻滞剂均无反应。结构性血管变化导致反应性增加，这可能解释了SHR中MAP变异性升高的原因。SHR的HR变异性明显降低；这不受迷走神经阻滞的影响，而WKY的HR变异性则明显降低。这种模式被认为是由于SHR中持续性轻度防御反应的一部分，迷走神经张力性放电减少所致。迷走神经活动的最初降低反过来又会消除迷走神经介导的心动过速。此外，对不同年龄的SHR给予β1阻滞剂导致MAP和HR的下降幅度大于WKY，这表明随着年龄的增长，SHR对交感神经系统的依赖性增加。
