The Different Changes of Phrenic Nerve Activity and Frequency Elicited by Microinjection of L-Glutamic Acid into Ventrolateral Nucleus of the Tractus Solitarius in Cats

微量麩氨酸注射於貓孤立束狀核腹外束引起各種不同膈神經衝動與頻率的改變

江啓輝(Chi-Huei Chiang) ； 黃基礎(Ji-Chuu Hwang)

《The Chinese Journal of Physiology》 33卷2期 (1990/06) Pp. 111-120

摘要

神經傳導物質在呼吸系統之調節知識仍很缺乏。過去研究曾指出麩氨酸(glutamic acid)可能是孤立束狀核(Nucleus of Tractus Solitarius, NTS)內的主要神經傳導物質，麩氨酸在呼吸中樞所扮演的角色如何仍不清楚。本文在於探討麩氨酸在孤立束狀核腹外束(Ventrolateral nucleus of the tractus solitarius)，亦即背側呼吸神經群(dorsal respiratory group, DRG)，對呼吸之影響。今利用Hamilton注射器，對去大腦貓微量注射麩氨酸至DRG，連續記錄膈神經衝動(phrenic nerve activity)，頻率(f)，吐氣末端二氧化碳含量，血壓及心跳。最後取腦幹固定並切片，以顯微鏡觀察注射位置是否於DRG。研究結果顯示，麩氨酸可導致各種不同膈神經衝動與頻率變化，如產生規則變化有(1)PNA與f皆增加(2)PNA與f減少(3)PNA減少但f增加(4)PNA與f皆減少，但亦可產生不規則變化如(1)PNA維持一段時間(2)一段時間沒產生PNA(3)PNA不規則的產生。同時根據組織切片，確定注射位置與注射後產生的呼吸變化，分析結果顯示背側呼吸神經群內並無特殊區專爲刺激或抑制呼吸的地方而是混雜在一起。因麩氨酸已證實爲神經傳導物質，由此研究，並參考其他學者研究結果，可推知孤立束狀核腹外束神經核內的神經細胞上具有麩氨酸的接受器，所以注射麩氨酸，才可刺激這些神經細胞，因有些神經細胞是與吸氣有關，有的則與呼氣有關。所以若注射不同位置，則產生不同的呼吸變化，據此可知麩氨酸可調節呼吸中樞對呼吸的管制。同時，我們大膽提出麩氨酸可能是呼吸中樞背側呼吸神經群的神經傳導物質，所以能主宰呼吸中樞對呼吸的管制。

並列摘要

There is only limited information of the neurotransmitters in central respiratory control. L-glutamic acid has been proposed as the primary neurotransmitter in the nucleus of the tractus solitarius (NTS) in cats. To test whether there is a respiratory effect of glutamic acid in the respiratory center or not, we microinjected L-glutamic acid (1 M, 0.1 μl) via 1μl Hamilton microsyringe into the ventrolateral nucleus of NTS, namely dorsal respiratory group (DRG) over two-second intervals with continuous monitoring of phrenic nerve activity (PNA), frequency (f), end tidal CO2, blood pressure and heart rate. Glutamate induced various respiratory changes including: increase in PNA and f. decrease in PNA and f. increase in PNA but decrease in f and decrease in PNA but increase in f. In addition to regular changes of PNA or f elicited by glutamate microinjection were found. Other patterns of irregular rhythmic changes such as absence of PNA, continuous phrenic nerve discharge and irregular phrenic nerve discharge with reflex apnea, apneusis and irregular respiration respectively were also observed. Glutamic acid appears to significantly modulate respiratory drive in DRG. We suggested that L-glutamic acid may be a neurotransmitter in the respiratory center and be involved in central respiratory control.

並列關鍵字

L-glutamic acid ； microinjection ； dorsal respiratory group ； phrenic nerve activity