Rothstein R D, DeRiso J, Ouyang A
Department of Medicine, University of Pennsylvania, Philadelphia 19104-4283.
Am J Physiol. 1990 Apr;258(4 Pt 1):G585-90. doi: 10.1152/ajpgi.1990.258.4.G585.
The ileocecal sphincter in the cat demonstrates a reflex contraction to colonic distension. This study investigates the pathway mediating this reflex in the intact bowel using an in vivo model. The ileocecal sphincter (ICS) and distal ileal intraluminal pressures were recorded in fasted chloralose-anesthetized cats. Colonic balloon distension caused a slight, but significant, ileal inhibition with a maximum decrease from resting ileal pressure by 2.6 +/- 0.76 mmHg (P less than 0.005) to 3 ml distension. A volume-dependent contraction at the ICS was seen with a maximal contraction of 16.8 +/- 2.2 mmHg (P less than 0.005) with 4 ml distension. The reflex ICS contraction was inhibited by tetrodotoxin and phentolamine but not by bilateral cervical vagotomy, naloxone, atropine, or trimethaphan camsylate. The reflex contraction at the ICS was inhibited by substance P tachyphylaxis. Substance P tachyphylaxis did not inhibit ICS contraction to phenylephrine. The substance P antagonist, [DArg1,DTrp7,9,Leu11]substance P failed to antagonize substance P and failed to inhibit the ICS contractile response to colonic balloon distension. Spinal anesthesia inhibited this reflex. We have thus demonstrated that the ICS reflex contraction to colonic balloon distension in the intact bowel is mediated by an extrinsic spinal neural pathway involving both tachykinin and catecholamines as neurotransmitters.
猫的回盲括约肌对结肠扩张表现出反射性收缩。本研究使用体内模型研究完整肠道中介导该反射的途径。在禁食并用氯醛糖麻醉的猫中记录回盲括约肌（ICS）和回肠远端腔内压力。结肠球囊扩张导致回肠轻微但显著的抑制，在3毫升扩张时，回肠压力从静息压力最大下降2.6±0.76毫米汞柱（P<0.005）。在ICS处观察到与体积相关的收缩，在4毫升扩张时最大收缩为16.8±2.2毫米汞柱（P<0.005）。反射性ICS收缩被河豚毒素和酚妥拉明抑制，但不受双侧颈迷走神经切断术、纳洛酮、阿托品或樟磺咪芬抑制。ICS处的反射性收缩被P物质快速耐受抑制。P物质快速耐受不抑制ICS对去氧肾上腺素的收缩。P物质拮抗剂[DArg1，DTrp7,9，Leu11]P物质未能拮抗P物质，也未能抑制ICS对结肠球囊扩张的收缩反应。脊髓麻醉抑制了该反射。因此，我们证明了完整肠道中ICS对结肠球囊扩张的反射性收缩是由一条涉及速激肽和儿茶酚胺作为神经递质的外在脊髓神经通路介导的。
