Brief Article
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World J Gastroenterol. Oct 14, 2012; 18(38): 5462-5469
Published online Oct 14, 2012. doi: 10.3748/wjg.v18.i38.5462
Effect of the ginsenoside Rb1 on the spontaneous contraction of intestinal smooth muscle in mice
Lei Xu, Sui-Ping Huang
Lei Xu, Scientific Research Station for Post-doctoral Studies, Post-doctoral Research Centre, Zhongshan Affiliated Hospital, Guangzhou University of Traditional Chinese Medicine, Zhongshan 528400, Guangdong Province, China
Sui-Ping Huang, Department of Gastroenterology, Guangdong Provincial Traditional Chinese Medicine Hospital, Ersha Island Branch, Guangzhou 510405, Guangdong Province, China
Author contributions: Xu L performed the experiment and wrote the paper; Huang SP designed the research and analysed the data.
Supported by National Natural Science Foundation of China, No. 30873328; The State Administration of Traditional Chinese Medicine of the People’s Republic of China, No. 06-075930
Correspondence to: Dr. Sui-Ping Huang, Department of Gastroenterology, Guangdong Provincial Traditional Chinese Medicine Hospital, Ersha Island Branch, Guangzhou 510405, Guangdong Province, China. doctorhsp@medmail.com.cn
Telephone: +86-20-87351238 Fax: +86-760-87602121
Received: January 31, 2012
Revised: May 8, 2012
Accepted: May 13, 2012
Published online: October 14, 2012
Abstract

AIM: To investigate the effect and the possible mechanism of ginsenoside Rb1 on small intestinal smooth muscle motility in mice.

METHODS: Intestinal smooth muscle strips were isolated from male ICR mice (5 wk old), and the effect of ginsenoside Rb1 on spontaneous contraction was recorded with an electrophysiolograph. The effect of ginsenoside Rb1 on ion channel currents, including the voltage-gated K+ channel current (IKV), calcium-activated potassium channel currents (IKCa), spontaneous transient outward currents and ATP-sensitive potassium channel current (IKATP), was recorded on freshly isolated single cells using the whole-cell patch clamp technique.

RESULTS: Ginsenoside Rb1 dose-dependently inhibited the spontaneous contraction of intestinal smooth muscle by 21.15% ± 3.31%, 42.03% ± 8.23% and 67.23% ± 5.63% at concentrations of 25 μmol/L, 50 μmol/L and 100 μmol/L, respectively (n = 5, P < 0.05). The inhibitory effect of ginsenoside Rb1 on spontaneous contraction was significantly but incompletely blocked by 10 mmol/L tetraethylammonium or 0.5 mmol/L 4-aminopyridine, respectively (n = 5, P < 0.05). However, the inhibitory effect of ginsenoside Rb1 on spontaneous contraction was not affected by 10 μmol/L glibenclamide or 0.4 μmol/L tetrodotoxin. At the cell level, ginsenoside Rb1 increased outward potassium currents, and IKV was enhanced from 1137.71 ± 171.62 pA to 1449.73 ± 162.39 pA by 50 μmol/L Rb1 at +60 mV (n = 6, P < 0.05). Ginsenoside Rb1 increased IKCa and enhanced the amplitudes of spontaneous transient outward currents from 582.77 ± 179.09 mV to 788.12 ± 278.34 mV (n = 5, P < 0.05). However, ginsenoside Rb1 (50 μmol/L) had no significant effect on IKATP (n = 3, P < 0.05).

CONCLUSION: These results suggest that ginsenoside Rb1 has an inhibitory effect on the spontaneous contraction of mouse intestinal smooth muscle mediated by the activation of IKV and IKCa, but the KATP channel was not involved in this effect.

Keywords: Ginsenoside Rb1; Intestinal smooth muscle; Intestinal smooth muscle cell; Potassium channel; Spontaneous contraction; Whole-cell patch clamp technique