Experimental study of chemical transmitter of the swallowing center in the patients with dysphasia

在α-氯醛糖和氨基甲酸乙酯深度麻醉的人工呼吸颈迷走神经切除猫上，我们观察了三叉神经脊髓核是否参与电刺激舌神经中央切断端引起下唇副交感神经反射血管扩张的中枢机制。为此，我们在脑干内进行微量注射，以产生非选择性、可逆的局部麻醉(利多卡因)或选择性的、不可逆的神经毒性损伤(海人酸)。微量注射利多卡因(2%；1μL/个部位)局麻下VSP，可逆性地降低同侧LN诱发的副交感神经反射血管扩张。刺激LN同侧VSP内微量注射红藻氨酸(10 mM/点，1μL)可使反射性血管扩张不可逆转地减弱，但对刺激对侧LN引起的血管扩张无明显影响。VSP内微量注射红藻氨酸对电刺激同侧下涎核引起的血管扩张无影响。无论全身动脉压是否下降，电刺激VSP均能以强度和频率依赖的方式引起下唇血流量增加。六甲溴铵(1.0 mg/kg，静脉注射)显著降低电刺激LN或VSP中央切断端引起的血管扩张反应，两者程度相似。服用六甲溴铵后，两种血管扩张剂反应均显示出时间依赖性的恢复。这些结果有力地表明，VSP是猫下唇LN诱发的副交感神经反射血管扩张的重要延髓中继物。

We examined whether the trigerainal spinal nucleus (Vsp) forms part of the central mechanism by which electrical stimulation of the central cut end of the lingual nerve (LN) evokes parasympathetic reflex vasodilatation in the lower lip in artificially ventilated, cervically vagosympathectomized cats deeply anesthetized with α-chloralose and urethane. For this purpose, we made microinjections within the brain stem to produce nonselective, reversible local anesthesia (lidocaine) or soma-selective, irreversible neurotoxic damage (kainic acid). Local anesthesia of Vsp by microinjection of lidocaine (2%; 1μl/site) reversibly and significantly reduced the ipsilateral-LN-evoked parasympathetic reflex vasodilatation. Unilateral microinjection of kainic acid(10mM/site; 1μl) into Vsp ipsilateral to the stimulated LN led to an irreversible reduction in the reflex vasodilatation but had no effect on the vasodilatation elicited by stimulation of the contralateral LN. Such microinjection of kainic acid into Vsp had no effect on the vasodilatation evoked by electrical stimulation of the ipsilateral inferior salivatory nucleus. Electrical stimulation of Vsp elicited a blood flow increase in the lower lip in an intensity- and frequency-dependent manner, regardless of whether systemic arterial blood pressure roseOr fell. Hexamethonium (1.0mg/kg, I. v.) significantly reduced the vasodilator responses elicited by electrical stimulation of the central cut end of LN or Vsp, each to a similar degree. After hexamethonium, both vasodilator responses showed time-dependent recovery. These results strongly suggest that Vsp is an important bulbar relay for LN-evoked parasympathetic reflex vasodilatation in the cat lower lip.