McKirdy H C, Richardson C E, Green J T, Rhodes J, Williams G T, Marshall R W
Department of Surgery, University of Wales College of Medicine, Cardiff, UK.
Br J Surg. 2004 Feb;91(2):229-34. doi: 10.1002/bjs.4395.
Nicotine has been shown to release nitric oxide from nerves in human sigmoid colon. This effect has been used to investigate the innervation and functional relationship of the longitudinal and circular muscle layers.
Strips of longitudinal and circular muscle were obtained from 19 patients with colorectal cancer. The strips from ten patients were subjected to electrical field stimulation (EFS) in vitro using stimulus parameters for selective stimulation of nerves. The effect of nicotine 1-10 micromol/l on EFS responses was then measured in the presence and absence of a nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (L-NAME) 200 micromol/l. The effect of nicotine on spontaneous activity was investigated in the muscle strips from the other nine patients.
Both longitudinal and circular strips responded to EFS with contraction. The time to achieve a peak contractile response (time to peak; TTP) was significantly longer (P<0.001) in circular strips. L-NAME reduced the mean(s.e.m.) TTP in circular muscle from 23.3(2.0) to 17.2(1.5) s (P=0.007) and altered its pattern of response to resemble that of longitudinal muscle. Nicotine 10 micromol/l reduced the contraction to EFS in circular (P<0.001) but not in longitudinal (P=0.347) muscle. The nicotine-induced reduction in circular muscle contraction was blocked by L-NAME 200 micromol/l (P=0.005).
These findings suggest that nitric oxide release on neural stimulation is greater in circular than in longitudinal muscle.
已证实尼古丁可使人乙状结肠神经释放一氧化氮。这一效应已被用于研究纵肌层和环肌层的神经支配及功能关系。
从19例结直肠癌患者获取纵肌和环肌条。对其中10例患者的肌条在体外使用选择性刺激神经的刺激参数进行电场刺激（EFS）。然后在存在和不存在200微摩尔/升一氧化氮合酶抑制剂硝基-L-精氨酸甲酯（L-NAME）的情况下，测量1-10微摩尔/升尼古丁对EFS反应的影响。在另外9例患者的肌条中研究尼古丁对自发活动的影响。
纵肌条和环肌条对EFS均有收缩反应。环肌条达到收缩峰值反应的时间（峰值时间；TTP）明显更长（P<0.001）。L-NAME使环肌的平均（标准误）TTP从23.3（2.0）秒降至17.2（1.5）秒（P=0.007），并改变其反应模式使其类似于纵肌。10微摩尔/升尼古丁使环肌对EFS的收缩减弱（P<0.001），但对纵肌无此作用（P=0.347）。200微摩尔/升L-NAME可阻断尼古丁引起的环肌收缩减弱（P=0.005）。
这些发现提示，神经刺激时一氧化氮在环肌中的释放量大于纵肌。
