Inputs to inhibitory neurons that mediate the baroreceptor reflex.

在尿素麻醉的家兔中，刺激腓肠神经，皮肤传入神经（a纤维），引起反射反应，包括早期的小兴奋成分，随后是肾交感神经活动的长时间抑制成分。双侧注射GABA拮抗剂双丘碱（4 nmol/位点）到交感神经兴奋网状脊髓神经元所在的吻侧腹外侧髓质（RVLM），以剂量依赖的方式减弱抑制成分，以及刺激主动脉神经a纤维（压力感受器传入神经）引起的抑制。双侧向尾侧腹外侧髓质（CVLM）注射神经毒性药物kainic酸（4 nmol/位点，3个位点/侧），减少了这些交感神经抑制反应，这里有轴突投射到RVLM的交感神经抑制神经元。综上所述，体细胞传入激活引起的交感神经抑制是由CVLM的神经元和RVLM的GABA受体介导的，与动脉压力感受器反射相关的交感神经抑制也是如此。双侧向CVLM注射犬尿酸（4 nmol/位点，3个位点/侧）不影响体交感反射反应，但减轻了由压力感受器传入神经激活产生的交感抑制。当压力感受器传入信号被激活时，CVLM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CVLM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.