McKitrick D J, Calaresu F R
Department of Physiology, The University of Western Ontario, London, Canada.
Brain Res. 1996 Dec 2;742(1-2):203-10. doi: 10.1016/s0006-8993(96)00971-7.
To investigate interactions between sites in the medulla which control the sympathetic (SNS) and the parasympathetic (PNS) nervous system, the activity of cardiovascular neurons in the rostral ventrolateral medulla (RVLM) was recorded during chemical stimulation of cardioinhibitory neurons in the nucleus ambiguus (NA). Cardioinhibitory sites in the NA were identified in urethane anesthetized rats. The spontaneous activity of single units in the RVLM was recorded and cardiovascular units were identified as units which displayed a cardiac cycle-related rhythmicity (CR) and decreased activity after i.v. phenylephrine. Of 55 units studied, 36 units were identified as cardiovascular and of these, 24 decreased activity after glutamate (GLU) microinjection in the NA, two units were excited and ten did not respond. Decreases in RVLM unit activity were positively correlated with the magnitude and duration of heart rate decreases elicited by GLU. Seven of the 24 units were tested for their response to microinjection of glycine (GLY) in the NA. GLY did not change firing frequency but did accentuate CR. These results demonstrate an inhibitory connection between the NA and RVLM which influences the rhythmicity of RVLM unit activity and provide clear evidence for functional interactions between the SNS and PNS within the central nervous system.
为了研究延髓中控制交感神经系统（SNS）和副交感神经系统（PNS）的位点之间的相互作用，在对疑核（NA）中的心脏抑制神经元进行化学刺激期间，记录了延髓头端腹外侧区（RVLM）心血管神经元的活动。在乌拉坦麻醉的大鼠中确定了NA中的心脏抑制位点。记录RVLM中单个单位的自发活动，并将心血管单位确定为显示与心动周期相关的节律性（CR）且在静脉注射去氧肾上腺素后活动降低的单位。在所研究的55个单位中，有36个单位被确定为心血管单位，其中24个在NA中微量注射谷氨酸（GLU）后活动降低，2个单位兴奋，10个单位无反应。RVLM单位活动的降低与GLU引起的心率降低的幅度和持续时间呈正相关。对24个单位中的7个进行了测试，以观察它们对NA中微量注射甘氨酸（GLY）的反应。GLY没有改变放电频率，但确实增强了CR。这些结果证明了NA和RVLM之间的抑制性联系，该联系影响RVLM单位活动的节律性，并为中枢神经系统内SNS和PNS之间的功能相互作用提供了明确的证据。
