Abstract：
We hypothesized that sympathetic hyperactivity and parasympathetic insuficiency in spontaneously hypertensive rats (SHR) underlie their exaggerated cardiovascular response to acute stress and impaired adaptation to repeated restraint stress exposure compared to Wistar-Kyoto rats (WKY). Cardiovascular responses to single (120 min) or repeated (daily 120 min for 1 week) restraint were measured by radiotelemetry and autonomic balance was evaluated by power spectral analysis of systolic blood pressure variability (SBPV) and heart rate variability (HRV). Baroreflex sensitivity (BRS) was measured by the pharmacological Oxford technique. Stress-induced pressor response and vascular sympathetic activity (low-frequency component of SBPV) were enhanced in SHR subjected to single restraint compared to WKY, whereas stress-induced tachycardia was similar in both strains. SHR exhibited attenuated cardiac parasympathetic activity (high-frequency component of HRV) and blunted BRS compared to WKY. Repeated restraint did not affect the stress-induced increase in blood pressure. However, cardiovascular response during the post-stress recovery period of the 7th restraint was reduced in both strains. The repeatedly restrained SHR showed lower basal heart rate during the dark (active) phase and slightly decreased basal blood pressure during the light phase compared to stress-naive SHR. SHR subjected to repeated restraint also exhibited attenuated stress-induced tachycardia, augmented cardiac parasympathetic activity, attenuated vascular sympathetic activity and improved BRS during the last seventh restraint compared to single-stressed SHR. Thus, SHR exhibited enhanced cardiovascular and sympathetic responsiveness to novel stressor exposure (single restraint) compared to WKY. Unexpectedly, the adaptation of cardiovascular and autonomic responses to repeated restraint was more effective in SHR.
摘要：
我们假设，与Wistar-Kyoto大鼠（WKY）相比，自发性高血压大鼠（SHR）的交感神经过度活跃和副交感神经缺乏症是其对急性应激的过度心血管反应和对反复约束应激暴露的适应性受损的基础。通过放射遥测法测量对单次（120分钟）或重复（每天120分钟，持续1周）约束的心血管反应，并通过收缩压变异性（SBPV）和心率变异性（HRV）的功率谱分析评估自主神经平衡。通过药理学牛津技术测量压力反射敏感性（BRS）。与WKY相比，单次约束的SHR中应激诱导的升压反应和血管交感神经活动（SBPV的低频成分）得到增强，而应激诱导的心动过速在两种菌株中相似。与WKY相比，SHR表现出减弱的心脏副交感神经活动（HRV的高频成分）和钝化的BRS。反复约束不会影响压力引起的血压升高。然而,两种菌株在第7次约束的应激后恢复期的心血管反应均降低。与无压力的SHR相比，反复受约束的SHR在黑暗（活动）阶段显示较低的基础心率，而在光亮阶段则显示出较低的基础血压。受到反复约束的SHR也表现出减弱的压力诱发的心动过速，增强心脏副交感神经活动，与单应力SHR相比，在最后第七次约束期间，血管交感神经活动减弱，BRS改善。因此，与WKY相比，SHR对新型应激源暴露（单一约束）表现出增强的心血管和交感神经反应。出乎意料的是,在SHR中,心血管和自主神经反应对重复约束的适应更有效.
