Talman W T, Perrone M H, Scher P, Kwo S, Reis D J
Brain Res. 1981 Jul 27;217(1):186-91. doi: 10.1016/0006-8993(81)90198-0.
Recent reports have suggested that the excitatory amino acid L-glutamate is a neurotransmitter released by baroreceptor afferent nerves at their termination in the nucleus tractus solitarii (NTS). In this study we have examined the effect on arterial pressure, heart rate and baroreflex activity of the glutamate antagonist glutamate diethyl ester (GDEE) microinjected into the NTS of 50 rats anesthetized with Chloralose. Bilateral injections of GDEE produced dose dependent transient hypertension. The threshold dose was 2.5 micrograms/NTS and at a dose of 15 micrograms/NTS a maximal rise in arterial pressure and heart rate (from 95 +/- 8.7 mm Hg to 153 +/- 6.4 mm Hg and from 322 +/- 14.7 beats/min to 364 +/- 16.2 beats/min respectively, P less than 0.001, n = 6) occurred. A dose of 15 micrograms/NTS also completely blocked the baroreflex when injections were made bilaterally and it totally antagonized the cardiovascular effects of L-glutamate when injected immediately prior to L-glutamate. The hypertension, the antagonism of L-glutamate, and the blockade of the baroreflex persisted for 20-30 min. In that L-glutamate mediates a baroreflex-like response upon injection into NTS and in that GDEE blocks that response while at the same time blocking the naturally occurring baroreflex, the data are consistent with L-glutamate being a neurotransmitter of baroreflex afferents.
最近的报告表明，兴奋性氨基酸L-谷氨酸是压力感受器传入神经在孤束核（NTS）终末释放的一种神经递质。在本研究中，我们检测了向50只用氯醛糖麻醉的大鼠的NTS中微量注射谷氨酸拮抗剂二乙基亚氨基二乙酸谷氨酸酯（GDEE）对动脉血压、心率和压力反射活动的影响。双侧注射GDEE产生剂量依赖性的短暂性高血压。阈剂量为2.5微克/ NTS，在剂量为15微克/ NTS时，动脉血压和心率出现最大升高（分别从95±8.7毫米汞柱升至153±6.4毫米汞柱，从322±14.7次/分钟升至364±16.2次/分钟，P＜0.001，n = 6）。当双侧注射15微克/ NTS的剂量时，也完全阻断了压力反射，并且在紧接L-谷氨酸之前注射时，它完全拮抗了L-谷氨酸的心血管效应。高血压、对L-谷氨酸的拮抗作用以及对压力反射的阻断持续20 - 30分钟。鉴于L-谷氨酸注入NTS时介导一种类似压力反射的反应，且GDEE阻断该反应，同时阻断自然发生的压力反射，这些数据与L-谷氨酸是压力反射传入神经的神经递质一致。
