Uc A, Murray J A, Conklin J L
Department of Pediatrics, University of Iowa College of Medicine, Iowa City, USA.
Gastroenterology. 1997 Aug;113(2):514-20. doi: 10.1053/gast.1997.v113.pm9247471.
BACKGROUND & AIMS: Peristaltic contraction of the esophagus and relaxation of the lower esophageal sphincter (LES) are mediated by nitric oxide (NO.)-producing myenteric nerves. NO synthase immunoreactivity and calcitonin gene-related peptide (CGRP) immunoreactivity colocalize in these nerves. CGRP relaxes the LES and decreases the amplitude of esophageal peristalsis. The aim of this study was to test the hypothesis that CGRP plays a role in nerve-induced responses of the esophagus.
Smooth muscle strips from the LES and the body of the esophagus were stimulated by an electrical field to evoke nerve-mediated responses.
CGRP decreased the amplitude and lengthened the latency of the off-response, and it relaxed the LES. Tetrodotoxin did not block the CGRP-induced LES relaxation. The CGRP antagonist CGRP 8-37 inhibited the effects of exogenous CGRP. It increased the amplitude and shortened the latency of the off-response, and it increased the resting tone of the LES. CGRP 8-37 did not inhibit LES relaxation or esophageal contraction. N omega-nitro-L-arginine abolished nerve-induced relaxation of the LES muscle and the esophageal off-response but not the relaxation produced by CGRP.
These data support the hypothesis that CGRP may decrease the LES basal tone and modulate the timing and amplitude of the esophageal off-responses.
食管的蠕动收缩和食管下括约肌（LES）的松弛由产生一氧化氮（NO）的肌间神经介导。一氧化氮合酶免疫反应性和降钙素基因相关肽（CGRP）免疫反应性在这些神经中共同定位。CGRP可使LES松弛并降低食管蠕动幅度。本研究的目的是验证CGRP在神经诱导的食管反应中起作用这一假说。
用电场刺激LES和食管体部的平滑肌条以诱发神经介导的反应。
CGRP降低了去极化反应的幅度并延长了其潜伏期，且使LES松弛。河豚毒素未阻断CGRP诱导的LES松弛。CGRP拮抗剂CGRP 8-37抑制了外源性CGRP的作用。它增加了去极化反应的幅度并缩短了其潜伏期，且增加了LES的静息张力。CGRP 8-37未抑制LES松弛或食管收缩。Nω-硝基-L-精氨酸消除了神经诱导的LES肌肉松弛和食管去极化反应，但未消除CGRP产生的松弛。
这些数据支持CGRP可能降低LES基础张力并调节食管去极化反应的时间和幅度这一假说。
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