[Effect of motilin on gastric smooth contraction induced by interstitial cells of Cajal].

OBJECTIVE

To investigate the role of interstitial cells of Cajal (ICC) in contraction of gastric smooth muscle and the effect of motilin on this role.

METHODS

Two kinds of smooth muscle segments with ICC were isolated from the pacemaker area at the upper 1/3 of stomach body and from the gastric antrum of 90 rats and immersed into Krebs solution and linked with tonotransducer to record their contraction. Both kinds of smooth muscle segments were divided into 5 groups equally: group A (control group), group B (methylene blue and intense illumination were used to destroy the ICC therein), group C (motilin was added into the Krebs solution), group D (both motilin and anti-motilin serum were added), and group E (motilin and atropin or hexahydroxy-quaternary ammonium were added).

RESULTS

stable contractile activity was recorded in these 2 kinds of smooth muscle segments with higher frequency and amplitude of contraction in those from the gastric antrum than those from the stomach body. The frequency and amplitude of contraction in the smooth muscle segments with the ICC destroyed by methylene blue and intense illumination were decreased by 80% approximately 90%. Motilin increased the frequency and amplitude of contraction in the smooth muscle segments from the gastric antrum and stomach body dose-dependently. Anti-motilin serum and atropin, but not hexahydroxy-quaternary ammonium blocked the effect of motilin. The smooth muscle segments with destroyed ICC showed no significant differences in the frequency and amplitude of contraction in comparison with the smooth muscle segments with destroyed ICC plus motilin.

CONCLUSION

The pacemaker cells of the contractile activity of gastric smooth muscle cells are ICC, Motilin regulates the gastric smooth muscle contraction initiated by ICC.