Hegarty A A, Hayward L F, Felder R B
Cardiovascular Center, University of Iowa College of Medicine, Iowa City.
Am J Physiol. 1995 Mar;268(3 Pt 2):H1086-95. doi: 10.1152/ajpheart.1995.268.3.H1086.
The effects of electrical and chemical stimulation of the area postrema (AP) on mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were examined in urethan- and pentobarbital sodium-anesthetized rats and in unanesthetized decerebrate rats. The AP was electrically stimulated over a range of frequencies (10-100 Hz) and intensities (10-80 microA) with a pulse duration of 0.2 or 1.0 ms. The excitatory amino acid L-glutamate (100 or 200 mM) was microinjected into the AP to preferentially stimulate neuronal cell bodies. In urethan-anesthetized rats, electrical stimulation of the AP decreased MAP and RSNA. In pentobarbital sodium-anesthetized rats, MAP and RSNA were markedly increased by AP stimulation. In unanesthetized decerebrate rats, increases in MAP and RSNA were also observed during electrical AP stimulation. Microinjection of L-glutamate had no effect on MAP and RSNA in anesthetized or in unanesthetized rats. These results indicate that electrical AP stimulation increases sympathetic output in the unanesthetized decerebrate rat and that anesthesia modifies this sympathetic response. The findings also suggest that peripheral responses to L-glutamate and electrical stimulation of the AP are mediated over different central pathways.
在乌拉坦和戊巴比妥钠麻醉的大鼠以及未麻醉的去大脑大鼠中，研究了最后区（AP）的电刺激和化学刺激对平均动脉压（MAP）和肾交感神经活动（RSNA）的影响。以0.2或1.0毫秒的脉冲持续时间，在一系列频率（10 - 100赫兹）和强度（10 - 80微安）范围内对AP进行电刺激。将兴奋性氨基酸L-谷氨酸（100或200毫摩尔）微量注射到AP中以优先刺激神经元细胞体。在乌拉坦麻醉的大鼠中，AP的电刺激降低了MAP和RSNA。在戊巴比妥钠麻醉的大鼠中，AP刺激使MAP和RSNA显著增加。在未麻醉的去大脑大鼠中，电刺激AP期间也观察到MAP和RSNA增加。向麻醉或未麻醉的大鼠微量注射L-谷氨酸对MAP和RSNA没有影响。这些结果表明，电刺激AP会增加未麻醉去大脑大鼠的交感神经输出，并且麻醉会改变这种交感反应。研究结果还表明，对L-谷氨酸的外周反应和AP的电刺激是通过不同的中枢途径介导的。
