Baroreflex inhibition of cardiac sympathetic outflow is attenuated by angiotensin II in the nucleus of the solitary tract
Baroreflex inhibition of cardiac sympathetic outflow is attenuated by angiotensin II in the nucleus of the solitary tract
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DOI：
10.1016/s0306-4522(00)00559-5
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发表时间：
2001-01-01
期刊：
影响因子：
3.3
通讯作者：
Paton, JFR
中科院分区：
文献类型：
--
作者：
Boscan, P;Allen, AM;Paton, JFR
动脉压的稳态调节由动脉压力感受器维持。这些受体的激活会抑制心脏的交感神经活动。众所周知，孤束核中的血管紧张素II可减弱压力感受器反射诱发的迷走神经心动过缓。在这里，我们确定了压力感受器反射的心脏交感成分是否可以被孤束核中的血管紧张素 II 调节。采用原位、动脉灌注的大鼠心脑干标本并记录交感下心神经。灌注压增加引起反射性心动过缓和下心神经活动抑制。在孤束核中微量注射血管紧张素 II (500 fmol) 可显着减弱反射性心动过缓和对下心神经活动的抑制 (P < 0.01)。后者是可逆的，并且对氯沙坦（一种血管紧张素 II 1 型受体拮抗剂）敏感。相比之下，外周化学感受器反射引起了下心脏神经活动的增加，而这种活动不受孤束核外源性应用血管紧张素II的影响。我们得出结论，在孤束核内，血管紧张素II对压力感受器反射控制去往心脏的交感神经活动发挥强大而特异性的抑制调节作用。我们认为，我们的数据可能具有与高血压相关的临床意义，高血压是一种大脑中血管紧张素 II 活性增强且压力感受反射功效降低的疾病。 (C) 2001 国际广播组织。由爱思唯尔科学有限公司出版。保留所有权利。
Homeostatic regulation of arterial pressure is maintained by arterial baroreceptors. Activation of these receptors results in an inhibition of sympathetic activity to the heart. It is known that angiotensin II in the nucleus tractus solitarii attenuates the baroreceptor reflex-evoked vagal bradycardia. Here, we determined whether the cardiac sympathetic component of the baroreceptor reflex could be modulated by angiotensin II in the nucleus of the solitary tract. An in situ, arterially perfused working heart-brainstem preparation of rat was employed and the sympathetic inferior cardiac nerve recorded. Increases in perfusion pressure caused a reflex bradycardia and inhibition of inferior cardiac nerve activity. Microinjection of angiotensin II (500 fmol) in the nucleus of the solitary tract attenuated significantly both the reflex bradycardia and inhibition of inferior cardiac nerve activity (P < 0.01). The latter was reversible and sensitive to losartan, an angiotensin II type 1 receptor antagonist. In contrast, the peripheral chemoreceptor reflex evoked an increase in inferior cardiac nerve activity that was not affected by angiotensin II applied exogenously in the nucleus of the solitary tract.We conclude that within the nucleus of the solitary tract angiotensin II exerts a powerful and specific inhibitory modulation of the baroreceptor reflex control of sympathetic nerve activity destined for the heart. We suggest that our data may have clinical implications relating to hypertension, a condition when angiotensin II activity is heightened in the brain and the efficacy of the baroreflex is reduced. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.