The ability of baroreflex activation to improve blood pressure and resistance vessel function in spontaneously hypertensive rats is dependent on stimulation parameters
The ability of baroreflex activation to improve blood pressure and resistance vessel function in spontaneously hypertensive rats is dependent on stimulation parameters
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DOI：
10.1038/s41440-021-00639-9
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发表时间：
2021-03-12
影响因子：
5.4
通讯作者：
Fazan Jr, Rubens
中科院分区：
文献类型：
--
作者：
Domingos-Souza, Gean;Santos-Almeida, Fernanda Machado;Fazan Jr, Rubens
通过电刺激颈动脉窦 (CS) 激活压力感受反射可有效降低血压。然而，刺激方案之间的差异对心血管结果的影响程度尚未确定。为了解决这个问题，我们研究了短期和长期（SD 和 LD）CS 刺激对自发性高血压大鼠 (SHR) 血流动力学和血管功能的影响。我们为动物配备微型电刺激器，该刺激器与位于左侧 CS 神经周围的电极相连，在有意识的动物中连续施加 48 小时间歇性 5/25 秒开/关 (SD) 或 20/20 秒开/关 (LD) 方脉冲（1 毫秒、3 V、30 Hz）。还研究了假手术对照组。我们测量了刺激前 60 分钟、方案开始 24 小时以及刺激停止后 60 分钟的平均动脉压 (MAP)、收缩压变异性 (SBPV)、心率 (HR) 和心率变异性 (HRV)。 SD 刺激可逆地降低刺激期间的 MAP 和 HR。 LD 刺激引起 MAP 下降，即使在刺激停止后这种下降仍然持续。刺激后记录时，SD 和 LD 对 SBPV 或 HRV 没有任何影响，表明自主活动没有适应。仅从 LD 刺激的大鼠中分离出的肠系膜阻力血管中，对去氧肾上腺素的收缩反应和对乙酰胆碱的舒张反应均增加。总之，压力反射激活调节血流动力学和诱导持久血管适应的能力关键取决于电参数和 CS 刺激的持续时间。
Baroreflex activation by electric stimulation of the carotid sinus (CS) effectively lowers blood pressure. However, the degree to which differences between stimulation protocols impinge on cardiovascular outcomes has not been defined. To address this, we examined the effects of short- and long-duration (SD and LD) CS stimulation on hemodynamic and vascular function in spontaneously hypertensive rats (SHRs). We fit animals with miniature electrical stimulators coupled to electrodes positioned around the left CS nerve that delivered intermittent 5/25 s ON/OFF (SD) or 20/20 s ON/OFF (LD) square pulses (1 ms, 3 V, 30 Hz) continuously applied for 48 h in conscious animals. A sham-operated control group was also studied. We measured mean arterial pressure (MAP), systolic blood pressure variability (SBPV), heart rate (HR), and heart rate variability (HRV) for 60 min before stimulation, 24 h into the protocol, and 60 min after stimulation had stopped. SD stimulation reversibly lowered MAP and HR during stimulation. LD stimulation evoked a decrease in MAP that was sustained even after stimulation was stopped. Neither SD nor LD had any effect on SBPV or HRV when recorded after stimulation, indicating no adaptation in autonomic activity. Both the contractile response to phenylephrine and the relaxation response to acetylcholine were increased in mesenteric resistance vessels isolated from LD-stimulated rats only. In conclusion, the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of CS stimulation.