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Updated: Feb 13, 2026

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats
Published on: September 27, 2017
Effect of oxytocin on contraction of rabbit proximal colon in vitro
Dong-Ping Xie1, Lian-Bi Chen, Chuan-Yong Liu
1Department of Physiology, School of Medicine, Shandong University, Jinan 250012, Shandong Province, China.
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 degrees ), bubbled continuously with 950 mL x L(-1) O(2) and 50 mL x L(-1) CO(2). Isometric spontaneous contractile responses to oxytocin or other drugs were recorded in circular and longitudinal muscle strips.
Results:
OT (0.1 U x 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 x L(-1)) decreased the mean contractile amplitude and the contractile frequency of CM and LM. Hexamethonium (10 micromol x L(-1)) partly blocked the inhibition of oxytocin (1 U x L(-1)) on the contractile frenquency of CM. N(omega))-nitro-L-arginine-methylester (L-NAME, 1 micromol x L (-1)), progesterone (32 micromol x L(-1)) and estrogen (2.6 micromol x 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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