BURN J H, GIBBONS W R
Br J Pharmacol Chemother. 1964 Jun;22(3):540-8. doi: 10.1111/j.1476-5381.1964.tb01708.x.
The inhibition of the pendular movements in a loop of rabbit ileum caused by stimulating the periarterial nerves in the mesentery depends on the calcium concentration in the bathing fluid. The inhibition is small when the concentration is low, and increases as the concentration rises. In the lower ranges of calcium concentration there is rarely any change in the response to noradrenaline, so that the increase in inhibition is due to an increase in the amount of noradrenaline released. The effect of calcium is antagonized by magnesium. In the presence of hyoscine, nicotine inhibits the ileum, and this inhibition also depends on the concentration of calcium. Acetylcholine can sometimes be shown to cause inhibition, and again this inhibition depends on the concentration of calcium. These and other experiments show a close similarity between the release of catechol amines from the adrenal medulla by acetylcholine and the release of noradrenaline from the postganglionic fibre by stimulation or by nicotine. In both instances the calcium concentration plays a decisive part.
刺激兔肠系膜动脉周围神经所引起的兔回肠肠袢摆动运动的抑制作用取决于浴液中的钙浓度。当钙浓度较低时，抑制作用较小，且随着浓度升高而增强。在较低钙浓度范围内，对去甲肾上腺素的反应很少有变化，因此抑制作用的增强是由于释放的去甲肾上腺素量增加所致。钙的作用可被镁拮抗。在存在东莨菪碱的情况下，尼古丁抑制回肠，且这种抑制作用也取决于钙浓度。有时可证明乙酰胆碱会引起抑制作用，同样这种抑制作用也取决于钙浓度。这些及其他实验表明，乙酰胆碱从肾上腺髓质释放儿茶酚胺与刺激或尼古丁使节后纤维释放去甲肾上腺素之间存在密切相似性。在这两种情况下，钙浓度都起决定性作用。
