Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Pathophysiol. Feb 15, 2016; 7(1): 150-159
Published online Feb 15, 2016. doi: 10.4291/wjgp.v7.i1.150
Neurophysiological mechanisms of bradykinin-evoked mucosal chloride secretion in guinea pig small intestine
Mei-Hua Qu, Wan-Sheng Ji, Ting-Kun Zhao, Chun-Yan Fang, Shu-Mei Mao, Zhi-Qin Gao
Mei-Hua Qu, Ting-Kun Zhao, Chun-Yan Fang, Shu-Mei Mao, Zhi-Qin Gao, Key Lab of Applied Pharmacology in Universities of Shandong, Weifang Medical University, Weifang 261053, Shandong Province, China
Wan-Sheng Ji, Department of Gastroenterology, Affiliated Hospital of Weifang Medical University, Weifang 261053, Shandong Province, China
Author contributions: Qu MH and Gao ZQ designed the study; Qu MH, Ji WS, Zhao TK, Fang CY, and Mao SM perform the experiments and data analysis; Qu MH wrote the paper.
Supported by Grants from the Shandong Provincial Natural Science Foundation, China, No. ZR2009CL047 and No. ZR2011HM043; the Scientific Research Foundation for Returned Scholars (Ministry of Education of China, 2011, 43th); Shandong Province Higher Educational Science and Technology Program, No. J14LK15; and Excellent Teachers International Training Cooperation Program of Shandong Province (for Yang XY and Qu MH).
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of the Weifang Medical University.
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Mei-Hua Qu, PhD, MD, Key Lab of Applied Pharmacology in Universities of Shandong, Department of Pharmacology, Weifang Medical University, 7166 Baotong West Street, Weifang 261053, Shandong Province, China. qumeihua@hotmail.com
Telephone: +86-536-8462466 Fax: +86-536-8462466
Received: February 28, 2015
Peer-review started: March 26, 2015
First decision: April 20, 2015
Revised: April 29, 2015
Accepted: September 2, 2015
Article in press: September 7, 2015
Published online: February 15, 2016
Abstract

AIM: To investigate the mechanism for bradykinin (BK) to stimulate intestinal secretomotor neurons and intestinal chloride secretion.

METHODS: Muscle-stripped guinea pig ileal preparations were mounted in Ussing flux chambers for the recording of short-circuit current (Isc). Basal Isc and Isc stimulated by BK when preincubated with the BK receptors antagonist and other chemicals were recorded using the Ussing chamber system. Prostaglandin E2 (PGE2) production in the intestine was determined by enzyme immunologic assay (EIA).

RESULTS: Application of BK or B2 receptor (B2R) agonist significantly increased the baseline Isc compared to the control. B2R antagonist, tetrodotoxin and scopolamine (blockade of muscarinic receptors) significantly suppressed the increase in Isc evoked by BK. The BK-evoked Isc was suppressed by cyclooxygenase (COX)-1 or COX-2 specific inhibitor as well as nonselective COX inhibitors. Preincubation of submucosa/mucosa preparations with BK for 10 min significantly increased PGE2 production and this was abolished by the COX-1 and COX-2 inhibitors. The BK-evoked Isc was suppressed by nonselective EP receptors and EP4 receptor antagonists, but selective EP1 receptor antagonist did not have a significant effect on the BK-evoked Isc. Inhibitors of PLC, PKC, calmodulin or CaMKII failed to suppress BK-induced PGE2 production.

CONCLUSION: The results suggest that BK stimulates neurogenic chloride secretion in the guinea pig ileum by activating B2R, through COX increasing PGE2 production. The post-receptor transduction cascade includes activation of PLC, PKC, CaMK, IP3 and MAPK.

Keywords: Brandykinin, Ussing chamber, Brandykinin receptor, Cyclooxygenase, Prostaglandin E, Chloride secretion

Core tip: Bradykinin (BK) can stimulate intestinal chloride secretion and the firing of intestinal secretomotor neurons in the small intestine, but the mechanism is not well understood. In this study, muscle-stripped guinea pig ileal preparations were mounted in Ussing flux chambers for the recording of short-circuit current (Isc). BK agonist and BK antagonist were added to check the Isc change. Inhibitors of the signal transductors were pre-incubated with the tissue for 10 min before evoking with BK, and the Isc change was recorded. The change of prostaglandin E2 (PGE2) secretion was detected by ELISA after treatment with BK for 3 h. Results suggest that BK stimulates neurogenic chloride secretion in the guinea pig ileum by activating B2 receptors on secretomotor neurons, activating cyclooxygenase-1, and stimulating PGE2 production. The post-receptor transduction cascade includes activation of PLC, PKC, CaMK, IP3, and MAPK.