Cardiac sympathetic afferent stimulation augments the arterial chemoreceptor reflex in anesthetized rats
Cardiac sympathetic afferent stimulation augments the arterial chemoreceptor reflex in anesthetized rats
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DOI：
10.1152/japplphysiol.00681.2006
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发表时间：
2007-01-01
影响因子：
3.3
通讯作者：
Wang, Wei
中科院分区：
文献类型：
--
作者：
Gao, Lie;Pan, Yan-Xia;Wang, Wei
众所周知，慢性心力衰竭(CHF)与化学感受器反射增强和心脏交感传入反射(CSAR)增强有关。CSAR的增大可能在CHF状态下增强的化学感受器反射中起重要作用，因为两种反射的交感输出涉及相同的中枢区域。我们确定了化学和电刺激CSAR是否增强了正常大鼠的化学感受器反射功能。麻醉下记录肾交感神经活动(RSNA)和平均动脉压(MAP)。采用单侧颈动脉内注射氰化钾(KCN)和尼古丁的方法检测化学感受器反射。我们发现：1)左室心外膜应用辣椒素可使KCN和尼古丁共同引起的升压反应和RSNA反应增强；2)电刺激左心交感神经中心端时，KCN引起的升压反应和RSNA反应均增强；3)预先脑室注射氯沙坦(500nmol)可完全阻断电刺激心脏交感神经引起的化学感受器反射的增强；4)双侧孤束核(NTS)内微量注射氯沙坦(250pmol)可完全阻断心外膜注射辣椒素所增强的化学感受器反射。这些结果表明，化学和电刺激CSAR均增强了化学感受器反射，特别是位于NTS的中枢Ang II在这些反射相互作用中起主要作用。
Chronic heart failure ( CHF) is well known to be associated with both an enhanced chemoreceptor reflex and an augmented cardiac " sympathetic afferent reflex" ( CSAR). The augmentation of the CSAR may play an important role in the enhanced chemoreceptor reflex in the CHF state because the same central areas are involved in the sympathetic outputs of both reflexes. We determined whether chemical and electrical stimulation of the CSAR augments chemoreceptor reflex function in normal rats. Under anesthesia, renal sympathetic nerve activity ( RSNA) and mean arterial pressure ( MAP) were recorded. The chemoreceptor reflex was tested by unilateral intra- carotid artery bolus injection of potassium cyanide ( KCN) and nicotine. We found that 1) left ventricular epicardial application of capsaicin increased the pressor responses and the RSNA responses to chemoreflex activation induced by both KCN and nicotine; 2) when the central end of the left cardiac sympathetic nerve was electrically stimulated, both the pressor and the RSNA responses to chemoreflex activation induced by KCN were increased; 3) pretreatment with intracerebroventricular injection of losartan ( 500 nmol) completely prevented the enhanced chemoreceptor reflex induced by electrical stimulation of the cardiac sympathetic nerve; and 4) bilateral microinjection of losartan ( 250 pmol) into the nucleus tractus solitarii ( NTS) completely abolished the enhanced chemoreceptor reflex by epicardial application of capsaicin. These results suggest that both the chemical and electrical stimulation of the CSAR augments chemoreceptor reflex and that central ANG II, specially located in the NTS, plays a major role in these reflex interactions.