The central adrenergic and noradrenergic neurotransmitter systems diffusively affect the operation of the spinal neural network and dynamically gauge central sympathetic outflow. Using in vitro splanchnic nerve-thoracic spinal cord preparations as an experimental model, this study examined the intraspinal α1-adrenoceptor-meidated modulation of sympathetic firing behaviors. Several sympathetic single-fiber activities were simultaneously recorded. Application of phenylephrine (Phe, an α1-adrenoceptor agonist) increased, decreased or did not affect spontaneous firing. A log-log plot of the change ratios of the average firing rates (AFR) versus their basal AFR displays a linear data distribution. Thus, the heterogeneity in α1-adrenoceptor-mediated responses is well described by a power law function. Phe-induced power-law firing modulation (plFM) was sensitive to prazosin (Prz, an α1-adrenoceptor antagonist). Heparin (Hep, a competitive IP3 receptor blocker) and chelerythrine (Che, a protein kinase C inhibitor) also caused plFM. Phe-induced plFM persisted in the presence of Hep; however, it was occluded by Che pretreatment. Pair-wise analysis of single-fiber activities revealed synchronous sympathetic discharges. Application of Phe, Hep or Che suppressed synchronous discharges in fiber pairs with apparent correlated firing (ACF) and induced or potentiated synchronous discharges in those without or with minimal ACF. Thus, the basal activities of the sympathetic preganglionic neurons participate in determining the responses mediated by the activation of α1-adrenoceptors. This deterministic factor, which is intrinsic to spinal neural networks, helps the supraspinal adrenergic and noradrenergic systems differentially control their widely distributed neural targets.

中文翻译：

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α1-肾上腺素能受体对交感神经放电的状态依赖性调节需要新生大鼠脊髓中的组成型 PKC 活性

中枢肾上腺素能和去甲肾上腺素能神经递质系统广泛地影响脊髓神经网络的运作并动态地测量中枢交感神经流出。本研究使用体外内脏神经-胸脊髓制剂作为实验模型，研究了脊髓内α1-肾上腺素受体介导的交感神经放电行为的调节。同时记录了几个交感神经单纤维活动。去氧肾上腺素（Phe，一种α1-肾上腺素能受体激动剂）的应用增加、减少或不影响自发性放电。平均燃烧率 (AFR) 与其基础 AFR 的变化率的对数图显示线性数据分布。因此，α1-肾上腺素受体介导的反应的异质性可以用幂律函数很好地描述。Phe 诱导的幂律放电调制 (plFM) 对哌唑嗪（Prz，一种 α1-肾上腺素受体拮抗剂）敏感。肝素（Hep，一种竞争性 IP3 受体阻滞剂）和白屈菜红碱（Che，一种蛋白激酶 C 抑制剂）也会引起 plFM。Phe 诱导的 plFM 在 Hep 存在下持续存在；然而，它被Che预处理挡住了。单纤维活动的成对分析显示同步交感神经放电。Phe、Hep 或 Che 的应用抑制了具有明显相关点火 (ACF) 的纤维对中的同步放电，并在没有或具有最小 ACF 的纤维对中抑制了诱导或增强的同步放电。因此，交感神经节前神经元的基础活动参与确定由 α1-肾上腺素受体激活介导的反应。这种确定性因素是脊髓神经网络固有的