Basic Research
Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 15, 2003; 9(1): 165-168
Published online Jan 15, 2003. doi: 10.3748/wjg.v9.i1.165
Effect of oxytocin on contraction of rabbit proximal colon in vitro
Dong-Ping Xie, Lian-Bi Chen, Chuan-Yong Liu, Jing-Zhang Liu, Ke-Jing Liu
Dong-Ping Xie, Lian-Bi Chen, Chuan-Yong Liu, Jing-Zhang Liu, Ke-Jing Liu, Department of Physiology, Medical School, Shandong University, Jinan 250012, Shandong Province, China
Author contributions: All authors contributed equally to the work.
Supported by Scientific Initiating Grants of Shandong University and Shandong Science Foundation
Correspondence to: Lian-Bi Chen, Department of Physiology, School of Medicine, Shandong University, Jinan 250012, Shandong Province, China.
Telephone: +86-531-8382037 Fax: +86-531-8382156
Received: June 8, 2002
Revised: June 23, 2002
Accepted: July 3, 2002
Published online: January 15, 2003

AIM: To investigate the effects of oxytocin (OT) on isolated rabbit proximal colon and its mechanism.

METHODS: Both longitudinal muscle (LM) and circular muscle (CM) were suspended in a tissue chamber containing 5 mL Krebs solution (37 °C), bubbled continuously with 950 mL·L-1 O2 and 50 mL·L-1 CO2. Isometric spontaneous contractile responses to oxytocin or other drugs were recorded in circular and longitudinal muscle strips.

RESULTS: OT (0.1 U·L-1) failed to elicit significant effects on the contractile activity of proximal colonic smooth muscle strips (P > 0.05). OT (1 to 10 U·L-1) decreased the mean contractile amplitude and the contractile frequency of CM and LM. Hexamethonium (10 μmol·L-1) partly blocked the inhibition of oxytocin (1 U·L-1) on the contractile frenquency of CM. Nω-nitro-L-arginine-methylester (L-NAME, 1 μmol·L-1), progesterone (32 μmol·L-1) and estrogen (2.6 μmol·L-1) had no effects on OT-induced responses.

CONCLUSION: OT inhibits the motility of proximal colon in rabbits. The action is partly relevant with N receptor, but irrelevant with that of NO, progesterone or estrogen.

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