Selective impairment of central mediation of baroreflex in anesthetized young adult Fischer 344 rats after chronic intermittent hypoxia
Selective impairment of central mediation of baroreflex in anesthetized young adult Fischer 344 rats after chronic intermittent hypoxia
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DOI：
10.1152/ajpheart.00358.2007
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发表时间：
2007-11-01
影响因子：
4.8
通讯作者：
Cheng, Zixi Jack
中科院分区：
文献类型：
--
作者：
Gu, He;Lin, Min;Cheng, Zixi Jack
慢性间歇性缺氧（CIH）后，心率（HR）的压力感受反射控制受损。然而，这种反应的地点和性质仍不清楚。我们检查了压力感受器传入神经、迷走神经传出神经和压力感受反射回路的中心部分。 Fischer 344 (F344) 大鼠暴露于室内空气 (RA) 或 CIH 35-50 天，然后用异氟烷麻醉、通气并插管以测量平均动脉血压 (MAP) 和 HR。通过测量综合主动脉降压神经 (ADN) 活性 (Int ADNA) 相对于基线值的百分比变化来表征压力感受器功能，以响应硝普钠和去氧肾上腺素诱导的 MAP 变化。将数据拟合到 S 形逻辑函数曲线。在氯胺酮-乙酰丙嗪麻醉下评估左侧 ADN 和右侧迷走神经电刺激的 HR 反应。与 RA 对照相比，CIH 显着增加了最大压力感受器增益或最大斜率、最大 Int ADNA 和 Int ADNA 范围（最大 - 最小 Int ADNA），而逻辑函数的其他参数没有变化。此外，CIH 增加了对迷走神经传出刺激的心动过缓反应的最大幅度，并缩短了从刺激开始到峰值反应的时间。相反，CIH 显着降低了对左侧 ADN 刺激的心动过缓反应的最大幅度，并增加了从刺激开始到峰值反应的时间。因此，CIH 降低了压力感受反射的中枢调节，但增强了压力感受器传入功能和迷走神经传出控制 HR。
Baroreflex control of heart rate (HR) is impaired after chronic intermittent hypoxia (CIH). However, the location and nature of this response remain unclear. We examined baroreceptor afferent, vagal efferent, and central components of the baroreflex circuitry. Fischer 344 (F344) rats were exposed to room air (RA) or CIH for 35-50 days and were then anesthetized with isoflurane, ventilated, and catheterized for measurement of mean arterial blood pressure (MAP) and HR. Baroreceptor function was characterized by measuring percent changes of integrated aortic depressor nerve (ADN) activity (Int ADNA) relative to the baseline value in response to sodium nitroprusside- and phenylephrine-induced changes in MAP. Data were fitted to a sigmoid logistic function curve. HR responses to electrical stimulation of the left ADN and the right vagus nerve were assessed under ketamine-acepromazine anesthesia. Compared with RA controls, CIH significantly increased maximum baroreceptor gain or maximum slope, maximum Int ADNA, and Int ADNA range (maximum - minimum Int ADNA), whereas other parameters of the logistic function were unchanged. In addition, CIH increased the maximum amplitude of bradycardic response to vagal efferent stimulation and decreased the time from stimulus onset to peak response. In contrast, CIH significantly reduced the maximum amplitude of bradycardic response to left ADN stimulation and increased the time from stimulus onset to peak response. Therefore, CIH decreased central mediation of the baroreflex but augmented baroreceptor afferent function and vagal efferent control of HR.