Liu Jianmin, Pehlivanov Nonko, Mittal Ravinder K
Division of Gastroenterology, San Diego Veterans Affairs Medical Center and University of California San Diego, San Diego, California 92161, USA.
Am J Physiol Gastrointest Liver Physiol. 2002 Dec;283(6):G1276-81. doi: 10.1152/ajpgi.00080.2002. Epub 2002 May 1.
Esophageal distension and transient lower esophageal sphincter (LES) relaxation (TLESR) are accompanied by simultaneous relaxation of the LES and inhibition of crural diaphragm. Recent studies indicate that baclofen decreases the frequency of TLESR; however, its effect on the crural diaphragm is not known. We evaluated the effects of baclofen on LES relaxation and crural diaphragm inhibition induced by gastric distension and esophageal distension in cats. Five adult cats underwent surgical implantation of wire electrodes into the crural and costal diaphragm for measurement of their EMG activity, respectively. One week after the surgery, animals were lightly sedated and recordings were performed using a manometry catheter equipped with a 2.5-cm balloon. The effects of baclofen (10 micromol/kg iv) on the graded esophageal distension and gastric distension-induced LES and crural diaphragm responses were studied. Distension of the esophagus and stomach induces relaxation of the LES and inhibition of the crural diaphragm, simultaneously. Baclofen blocks both the esophageal and the gastric distension-induced relaxation of the LES and inhibition of the crural diaphragm. The magnitude of response to baclofen was significantly larger for the crural diaphragm inhibition than for the LES relaxation. Baclofen, a GABA(B) receptor agonist, blocks the reflex inhibitory pathway to the LES and crural diaphragm. The reflex inhibitory pathway to the crural diaphragm is more sensitive to blockade by baclofen than the reflex LES inhibitory pathway.
食管扩张和一过性下食管括约肌（LES）松弛（TLESR）伴随着LES的同时松弛和膈脚的抑制。最近的研究表明，巴氯芬可降低TLESR的频率；然而，其对膈脚的作用尚不清楚。我们评估了巴氯芬对猫胃扩张和食管扩张诱导的LES松弛和膈脚抑制的影响。五只成年猫接受手术，分别将线状电极植入膈脚和肋膈，以测量其肌电图活动。手术后一周，动物轻度镇静，并使用配备2.5厘米气囊的测压导管进行记录。研究了巴氯芬（10微摩尔/千克静脉注射）对分级食管扩张和胃扩张诱导的LES及膈脚反应的影响。食管和胃扩张同时诱导LES松弛和膈脚抑制。巴氯芬可阻断食管和胃扩张诱导的LES松弛及膈脚抑制。巴氯芬对膈脚抑制的反应幅度明显大于对LES松弛的反应幅度。巴氯芬，一种γ-氨基丁酸（B）受体激动剂，可阻断至LES和膈脚的反射性抑制通路。至膈脚的反射性抑制通路比反射性LES抑制通路对巴氯芬的阻断更敏感。
