Cardwell B A, Rubin M R, Snape W J, Cohen S
Am J Physiol. 1981 Sep;241(3):G222-6. doi: 10.1152/ajpgi.1981.241.3.G222.
The purpose of this study was to determine the length-tension properties and the response to neurohumoral agents of the feline ileocecal sphincter (ICS) circular smooth muscle in vitro. The ICS muscle during stretch maintained a higher resting tension at lower degrees of stretch than did the adjacent ileum and colon. Sodium nitroprusside (10(-3) M) or calcium-free Krebs solution with EGTA (5.0 mM) reduced the resting tension of ICS muscle by 15.8 +/- 2.1 and 19.1 +/- 2.5%, respectively. The ICS response to KCl depolarization was lower (0.37 +/- 0.03 kg/cm2) than colonic muscle (0.55 +/- 0.06 kg/cm2) oe ileal muscle (0.51 +/- 0.04 kg/cm2) (P less than 0.05). However, in response to acetylcholine, ICS muscle tension was minimal (0.06 +/- 0.02 kg/cm2) was compared with the colon (0.49 +/- 0.05 kg/cm2) or ileum (0.53 +/- 0.05 kg/cm2) (P less than 0.01). The ICS muscle contracted in response to phenylephrine, whereas other muscles were inhibited. Secretin, gastrin, glucagon, and cholecystokinin failed to act on the ICS muscle while other muscles did respond. These studies suggest that ICS muscle differs from adjacent ileal and colonic circular muscle in that a) in response to stretch it develops a high resting tension that is relatively resistant to calcium withdrawal, and b) it also shows quantitative and qualitative differences in response to neurohumoral agents.
本研究的目的是在体外确定猫回盲括约肌（ICS）环形平滑肌的长度-张力特性以及对神经体液因子的反应。在拉伸过程中，ICS肌肉在较低拉伸程度下比相邻的回肠和结肠保持更高的静息张力。硝普钠（10⁻³ M）或含EGTA（5.0 mM）的无钙Krebs溶液分别使ICS肌肉的静息张力降低15.8±2.1%和19.1±2.5%。ICS对氯化钾去极化的反应（0.37±0.03 kg/cm²）低于结肠肌肉（0.55±0.06 kg/cm²）或回肠肌肉（0.51±0.04 kg/cm²）（P<0.05）。然而，对乙酰胆碱的反应中，ICS肌肉张力最小（0.06±0.02 kg/cm²），与结肠（0.49±0.05 kg/cm²）或回肠（0.53±0.05 kg/cm²）相比（P<0.01）。ICS肌肉对去氧肾上腺素产生收缩反应，而其他肌肉则受到抑制。促胰液素、胃泌素、胰高血糖素和胆囊收缩素对ICS肌肉无作用，而其他肌肉有反应。这些研究表明，ICS肌肉与相邻的回肠和结肠环形肌肉不同，在于：a）对拉伸的反应中，它产生相对抗钙撤离的高静息张力；b）对神经体液因子的反应也表现出数量和质量上的差异。
