MICROINJECTION OF L-GLUTAMATE INTO THE NUCLEUS-TRACTUS-SOLITARII INCREASES ARTERIAL-PRESSURE IN CONSCIOUS RATS
MICROINJECTION OF L-GLUTAMATE INTO THE NUCLEUS-TRACTUS-SOLITARII INCREASES ARTERIAL-PRESSURE IN CONSCIOUS RATS
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DOI：
10.1016/0006-8993(92)90618-j
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发表时间：
1992-03-27
期刊：
影响因子：
2.9
通讯作者：
BONAGAMBA, LGH
中科院分区：
文献类型：
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作者：
MACHADO, BH;BONAGAMBA, LGH
将L-谷氨酸微量注射到麻醉大鼠的孤束核（NTS）中产生与压力感受器传入激活期间观察到的相似的平均动脉压（MAP）下降。 在本研究中，我们研究了通过长期植入套管在清醒自由活动大鼠的NTS中双侧微量注射L-谷氨酸的效果。 第I组（n = 6）在清醒状态下进行研究，24 h后用乌拉坦麻醉大鼠并重新检查L-谷氨酸的作用。 在清醒大鼠中，L-谷氨酸盐（30 pmol至5 nmol/100 nl）使MAP呈剂量依赖性增加（+37 +/- 7 mmHg，5 nmol），而在乌拉坦麻醉下观察到MAP福尔斯（-11 +/- 3 mmHg，5 nmol）。 Ⅱ组（n = 7）在清醒状态下进行研究，1 h后用氯醛糖麻醉大鼠，并重新检查L-谷氨酸的作用。 在这组清醒大鼠中，L-谷氨酸（300 pmol至5 nmol/100 nl）也产生了MAP的剂量依赖性增加（+37 +/- 5 mmHg，5 nmol），而在氯醛糖麻醉下，观察到了剂量依赖性降压反应（-33 +/- 6 mmHg，5 nmol）。 将生理盐水微量注射到清醒和麻醉大鼠的NTS中产生的影响可以忽略不计。 这些数据表明，在清醒的动物中，将L-谷氨酸微量注射到大鼠的NTS中产生升压反应，而在用氯醛糖或氨基甲酸乙酯麻醉的动物中产生降压反应。 本研究表明，在NTS的L-谷氨酸的反应强烈的影响麻醉，并强调需要在清醒的大鼠进行进一步的研究，以评估可能参与的L-谷氨酸在NTS的心血管反射。
Microinjection of L-glutamate into the nucleus tractus solitarii (NTS) of anesthetized rats produces a fall in mean arterial pressure (MAP) similar to that observed during activation of baroreceptor afferents. In the present study we examined the effect of bilateral microinjections of L-glutamate through chronically implanted cannulae in the NTS of conscious freely moving rats. Group I (n = 6) was studied under conscious conditions and 24 h later the rats were anesthetized with urethane and the effects of L-glutamate re-examined. In conscious rats, L-glutamate (30 pmol to 5 nmol/100 nl) produced dose-dependent increases in MAP (+37 +/- 7 mmHg, 5 nmol), whereas under urethane anesthesia falls in MAP were observed (-11 +/- 3 mmHg, 5 nmol). Group II (n = 7) was studied under conscious conditions and 1 h later the rats were anesthetized with chloralose and the effects of L-glutamate re-examined. In this group of conscious rats L-glutamate (300 pmol to 5 nmol/100 nl) also produced dose-dependent increases in MAP (+37 +/- 5 mmHg, 5 nmol), whereas under chloralose anesthesia a dose-dependent depressor response was observed (-33 +/- 6 mmHg, 5 nmol). Saline microinjections into the NTS of conscious and anesthetized rats produced negligible effects. These data demonstrate that microinjection of L-glutamate into the NTS of rats produces a pressor response in conscious animals in contrast to depressor responses in animals anesthetized with chloralose or urethane. The present study indicates that responses to L-glutamate in the NTS are strongly influenced by anesthesia and emphasize the need for further studies in conscious rats to evaluate the possible involvement of L-glutamate in the cardiovascular reflexes in the NTS.