Properties of acetylcholine-induced relaxation of smooth muscle isolated from the proximal colon of the guinea-pig

DOI Web Site 被引用文献3件 参考文献17件

この論文をさがす

抄録

The properties of mechanical responses elicited by stimulation with acetylcholine (ACh) were investigated in circular smooth muscle preparations isolated from the proximal colon of guinea-pig. Application of ACh (10–8–10–6 M) for 3–5 min produced a biphasic response, with an initial contraction followed by a relaxation. Atropine inhibited the initial contraction, while Nω-nitro-L-arginine (L-NA) inhibited the relaxation, suggesting that the former was produced by activation of muscarinic receptors while the latter was produced by an elevated production of nitric oxide (NO). In the presence of atropine, the ACh-relaxation was attenuated by removal of the mucosa and abolished by removal of both submucosal and mucosal layers. The ACh-induced relaxation was also attenuated by either tetrodotoxin (TTX, 3 × 10–7 M) or hexamethonium (10–6 M). In the presence of atropine, transmural nerve stimulation (TNS) elicited a biphasic response, with an initial phasic contraction followed by a relaxation. The amplitude of TNS-induced relaxation was significantly reduced by hexamethonium or L-NA and was abolished by TTX. Both ACh and TNS produced relaxation in preparations isolated from the proximal colon, but not in those from the middle part of colon. Immunohistochemistry for neuronal nitric oxide synthase revealed no difference in the distribution of nitrergic nerves between the proximal and middle part of the colon, with nitrergic nerves in both the mucosal and submucosal layers as well as in the smooth muscle and myenteric layers. These results suggest that ACh induces NO production by excitation of postganglionic nerves distributed mainly in the mucosal and submucosal layers. In circular smooth muscle preparations isolated from the middle part of colon, ACh or TNS produced contractile responses alone, with no associated relaxation, suggesting that the ACh-activated postganglionic nitrergic nerves are distributed in the mucosal and submucosal layers of the proximal colon but not in the middle part of the colon.<br>

収録刊行物

被引用文献 (3)*注記

もっと見る

参考文献 (17)*注記

もっと見る

関連プロジェクト

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ