ABSTRACT
AIM: To evaluate effects of Pinaverium Bromide on different segments and layers of colonic smooth muscle in wrap restraint stress (WRS) rats and explore its possible therapeutic mechanism on different types of irritable bowel syndrome (IBS). METHODS: Adult SD rats were randomly divided into model group (wrap restraint stress group) and control group. Colonic smooth muscle strips were made from different segments and layers in two groups. The spontaneous contraction activities of colonic longitudinal/circular muscle (LM/CM) strips of rats were observed with organ bath system before and after addition of series concentrations of pinaverium. RESULTS: Pinaverium Bromide caused concentration-dependent inhibition of colonic smooth muscle, the inhibitory effect of pinaverium in model group was significantly stronger than that in control group(proximal colon: 28.54±4.82 vs 7.48±1.65,21.75±1.00 vs 12.56±3.15; distal colon: 15.71±5.27 vs 3.89±1.16, 20.16±3.16 vs 7.56±1.96 )(P<0.05). Compared with that of distal colon, inhibitory effect of pinaverium was significantly higher of proximal colon (P<0.05). For the inhibition of pinaverium, there was no significant difference between LM and CM strips in the same intestinal segments (P>0.05). CONCLUSION: Effects of Pinaverium Bromide on different colonic muscle layers and segments in WRS rats is probably related with its therapeutic mechanism on different types of IBS.