咪唑克生拮抗异丙肾上腺素对小鼠小肠运动的抑制

Antagonism Idazoxan to the Inhibition of Isoprenaline on Motility of Small Intestine in Mice

为了解去甲肾上腺素对小肠运动的抑制是否是因激动α２受体所致，试验了肾上腺素受体激动剂和拮抗剂对小鼠小肠转运印度墨汁的影响。药物均皮下注射。结果：α、β受体激动剂ＮＥ４ｍｇ／ｋｇ，β受体激动剂异丙肾上腺素（ＩＳＯ）１０ｍｇ／ｋｇ和α２受体激动剂噻拉嗪１．５ｍｇ／ｋｇ均抑制小肠运动；α２受体激动剂去氧肾上腺素１０ｍｇ／ｋｇ，甲氧明１０ｍｇ／ｋｇ，β１受体激动剂沙丁胺醇１０ｍｇ／ｋｇ皆无影响。ＮＥ和ＩＳＯ的这一作用被α２受体拮抗剂咪唑克生１ｍｇ／ｋｇ拮抗，而不被α１受体激动剂哌唑嗪１ｍｇ／ｋｇ和β受体拮抗剂普萘洛尔１０ｍｇ／ｋｇ拮抗。这提示，无论是ＮＥ或ＩＳＯ，都是作用于α２受体抑制小肠运动。

ecently it was shown that the inhibitory effect of norepinephrine (NE) on defecation in mice was antagonized by idazoxan (Ida), but not affected by prazosin (Pra) and propranolol (Pro). In this paper, whether NE and related drugs produce a similar action on the motility of small intestine was examined by the transportation of Indian ink in the intestinal tract.Subcutaneous injections of NE (4 mg·kg1),isoprenaline (Iso,10 mg·kg1) and xylazine (1.5 mg·kg1) inhibited the passage of ink significantly. In contrast, phenylnephrine (10 mg·kg1), methoxamine (10 mg·kg1),dobutamine (10 mg·kg1) and salbutamol (10 mg·kg1) did not show significant effect. Furthermore, the inhibitory effect of NE and Iso was antagonized by Ida (1 mg·kg1),but not by Pra (1 mg·kg1) and Pro (10 mg·kg). These results suggest that the inhibition of intestinal motility induced by NE and Iso is mediated via a2 adrenoceptors.