Inputs to inhibitory neurons that mediate the baroreceptor reflex.

在乌拉坦麻醉的兔，刺激腓肠神经，皮肤传入(A纤维)，诱发的反射反应由早期的小的兴奋成分组成，随后是肾交感神经活动的延长的抑制成分。向交感-兴奋性网状脊髓神经元所在的延髓头端腹外侧区(RVLM)注射GABA拮抗剂荷包牡丹碱(4nmol/Site)，以剂量依赖的方式减弱抑制成分和刺激主动脉神经A纤维(压力感受器传入)引起的抑制。双侧延髓尾侧腹外侧区(CVLM)注射神经毒剂红藻氨酸(4nmol/个，3个/侧)，可减弱这些交感抑制反应。因此，我们认为激活躯体传入引起的交感抑制与动脉压力感受性反射有关的交感抑制是由CVLM内的神经元和RVLM内的GABA受体所介导的。双侧CVLm内注射犬尿酸(4nmoL/个，3个/侧)不影响体感神经反射反应，但可减弱压力感受器传入所产生的交感抑制。当压力感受器传入被激活时，CVLM内的交感抑制神经元被谷氨酸激活，但另一种兴奋性递质可能参与了CVLM内的躯体-交感反射。

In urethane-anesthetized rabbits, stimulation of the sural nerve, cutaneous afferents (A-fibers), evoked reflex responses consisting of an early small excitatory component followed by a prolonged inhibitory component in renal sympathetic nerve activity. Bilateral injections of GABA antagonist, bicuculline (4 nmol/site), into the rostral ventrolateral medulla (RVLM), where sympatho-excitatory reticulospinal neurons are located, attenuated the inhibitory component in a dose-dependent manner as well as the inhibition evoked by stimulation of the aortic nerve A-fibers (baroreceptor afferents). Bilateral injections of a neurotoxic agent, kainic acid (4 nmol/site, 3 sites/side),into the caudal ventrolateral medulla (CVLM), where sympatho-inhibitory neurons with axonal projection to the RVLM are located, diminished these sympatho-inhibitory responses. Therefore, it is concluded that the sympatho-inhibition evoked by activation of somatic afferents was mediated by neurons in the CVLM and by GABA receptors in the RVLM, as also was the sympatho-inhibition associated with the arterial baroreceptor reflex. Bilateral injections of kynurenic acid (4 nmol/site, 3 sites/side) into the CVLM did not affect the somatosympathetic reflex response, but diminished the sympatho-inhibition produced by activation of the baroreceptor afferents. Sympatho-inhibitory neurons in the CVLM were activated by glutamate when baroreceptor afferents were activated, but another excitatory transmitter may participate in the somato-sympathetic reflex in the CVLM.