Uc A, Oh S T, Murray J A, Clark E, Conklin J L
Department of Pediatrics, University of Iowa College of Medicine and Department of Veterans Affairs Medical Center, Iowa City, Iowa 52242, USA.
Am J Physiol. 1999 Sep;277(3):G548-54. doi: 10.1152/ajpgi.1999.277.3.G548.
Vasoactive intestinal polypeptide (VIP) and nitric oxide (NO.) are thought to mediate lower esophageal sphincter (LES) relaxation. Transverse muscle strips from the opossum LES were used to test this hypothesis. Electrical field stimulation (EFS) produced a biphasic LES relaxation: a rapid component during the stimulus was more prominent at lower stimulus frequencies, and a sustained component was more prominent at higher frequencies. N(omega)-nitro-L-arginine and hemoglobin inhibited the rapid component but affected the sustained component less. Exogenous VIP decreased LES tone. A number of purported VIP antagonists blocked neither VIP-induced nor EFS-induced relaxation of the LES. The calcitonin gene-related peptide (CGRP) antagonist CGRP-(8-37) did not alter EFS-induced LES relaxation. EFS-induced relaxation of opossum LES muscle is biphasic, and the initial, rapid component of the relaxation is mediated primarily by NO. The mediator of the sustained component was not identified.
血管活性肠肽（VIP）和一氧化氮（NO.）被认为介导食管下括约肌（LES）松弛。用负鼠LES的横肌条来检验这一假设。电场刺激（EFS）产生双相性LES松弛：刺激期间的快速成分在较低刺激频率时更显著，而持续成分在较高频率时更显著。N（ω）-硝基-L-精氨酸和血红蛋白抑制快速成分，但对持续成分影响较小。外源性VIP降低LES张力。一些所谓的VIP拮抗剂既不阻断VIP诱导的也不阻断EFS诱导的LES松弛。降钙素基因相关肽（CGRP）拮抗剂CGRP-（8-37）不改变EFS诱导的LES松弛。EFS诱导的负鼠LES肌肉松弛是双相性的，松弛的初始快速成分主要由NO介导。持续成分的介质尚未确定。
