Involvement of trigeminal spinal nucleus in parasympathetic reflex vasodilatation in cat lower lip

Kentaro Mizuta, Satoshi Kuchiiwa, Takashi Saito, Hideaki Mayanagi, Keishiro Karita, Hiroshi Izumi

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

We examined whether the trigeminal 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%; 1 μl/site) reversibly and significantly reduced the ipsilateral-LN-evoked parasympathetic reflex vasodilatation. Unilateral microinjection of kainic acid (10 mM/site; 1 μl) 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 rose or fell. Hexamethonium (1.0 mg/kg iv) significantly reduced the vasodilator responses elicited by electrical stimulation of the central cut end of LN or of 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.

Original languageEnglish
Pages (from-to)R492-R500
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume282
Issue number2 51-2
Publication statusPublished - 2002 Jul 2

Keywords

  • Autonomic ganglion blocker
  • Autonomic reflex
  • Kainic acid
  • Lidocaine

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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