Hsu W H, Shaw R N, Schaffer D D, Crump M H, Greer M H
Arch Int Pharmacodyn Ther. 1987 Mar;286(1):145-51.
The effect of amitraz, a formamidine insecticide, on in vitro intestinal contractions was studied in teh transmurally-stimulated guinea-pig ileum. An electrical stimulation (with 80 V/0.5 msec/0.1 Hz shown on the dial of the stimulator) caused the ileum to contract presumably via the release of acetylcholine. Amitraz (10(-7) to 10(-6) M) produced a dose-dependent inhibition of these transmurally-stimulated contractions. This effect of amitraz was blocked and reversed by idazoxan (10(-6) M), an alpha 2-adrenoceptor antagonist, but was not prevented by prazosin (10(-6) M), an alpha 1-adrenoceptor antagonist. These results suggest that alpha 2-adrenoceptors mediate the effects of amitraz on the transmurally-stimulated guinea-pig ileum. The results also suggest that amitraz decreases intestinal contraction by activating the alpha 2-adrenoceptors in the myenteric (Auerbach's) plexus, thus inhibiting parasympathetic tone.
在经壁刺激的豚鼠回肠中研究了甲脒类杀虫剂双甲脒对体外肠道收缩的影响。电刺激（刺激器刻度盘显示为80V/0.5毫秒/0.1赫兹）可能通过乙酰胆碱的释放导致回肠收缩。双甲脒（10^-7至10^-6 M）对这些经壁刺激的收缩产生剂量依赖性抑制。双甲脒的这种作用被α2肾上腺素能受体拮抗剂咪唑克生（10^-6 M）阻断并逆转，但未被α1肾上腺素能受体拮抗剂哌唑嗪（10^-6 M）阻止。这些结果表明，α2肾上腺素能受体介导双甲脒对经壁刺激的豚鼠回肠的作用。结果还表明，双甲脒通过激活肌间（奥尔巴赫）神经丛中的α2肾上腺素能受体来减少肠道收缩，从而抑制副交感神经张力。
