Pelckmans P A, Boeckxstaens G E, Van Maercke Y M, Herman A G, Verbeuren T J
Department of Medicine, University of Antwerp (UIA), Belgium.
Eur J Pharmacol. 1989 Nov 7;170(3):235-42. doi: 10.1016/0014-2999(89)90544-x.
The effects of cholinergic agents, electrical stimulation and vasoactive intestinal polypeptide (VIP) were studied on transverse muscle strips of the canine ileum, ileocolonic junction and colon. Acetylcholine, methacholine and carbachol caused concentration-dependent contractions in the three gut tissues. Only acetylcholine (greater than 10(-5) M) evoked transient relaxations in the ileum and the ileocolonic junction before the onset of contractions. During contractions by noradrenaline, acetylcholine induced relaxations, which were enhanced by atropine; electrical stimulation also caused frequency-dependent relaxations. Propranolol or naloxone did not affect the relaxations. Hexamethonium, cocaine or lidocaine inhibited the relaxations induced by acetylcholine but not those evoked by electrical stimuli. Tetrodotoxin inhibited all relaxations, VIP did not evoke relaxation in the ileocolonic junction. These data indicate that acetylcholine stimulates nicotinic receptors on non-adrenergic non-cholinergic neurons, which do not release VIP or opioids. It is thus suggested that there is a nicotinic inhibitory innervation at the canine ileum and ileocolonic junction.
研究了胆碱能药物、电刺激和血管活性肠肽（VIP）对犬回肠、回结肠交界处和结肠横肌条的影响。乙酰胆碱、醋甲胆碱和卡巴胆碱在三种肠道组织中引起浓度依赖性收缩。只有乙酰胆碱（大于10⁻⁵M）在收缩开始前在回肠和回结肠交界处引起短暂松弛。在去甲肾上腺素引起收缩期间，乙酰胆碱诱导松弛，阿托品可增强这种松弛；电刺激也引起频率依赖性松弛。普萘洛尔或纳洛酮不影响松弛。六甲铵、可卡因或利多卡因抑制乙酰胆碱诱导的松弛，但不抑制电刺激引起的松弛。河豚毒素抑制所有松弛，VIP在回结肠交界处不引起松弛。这些数据表明，乙酰胆碱刺激非肾上腺素能非胆碱能神经元上的烟碱受体，这些神经元不释放VIP或阿片类物质。因此，提示犬回肠和回结肠交界处存在烟碱抑制性神经支配。
