[Effects of emodin on the activity of K channel in guinea pig taenia coli smooth muscle cells].

The effects of emodin, cromakalim (KATP channel opener) glybenclamide (KATP channel inhibitor) Ba2+ and TEA on the electrical and contractive activities of the smooth muscle cells in guinea pig taenia coli and the relationship between emodin and four other drugs were studied by using intracellular microelectrode technique and the tension measuring technique. The results are as follows: (1) Emodin enhances the electrical and contractive activities of the smooth muscle cells in guinea pig taenia coli. The effects of emodin depend on its concentration. (2) Emodin can resist the inhibition of cromakalim on the electrical and contractive activities of smooth muscle cells. On the other hand, cromakalim was shown to suppress the effects of emodin. (3) Ba2+, TEA and glybenclamide all can improve the electrical and contractive activities of smooth muscle cells and resist the inhibition of cromakalim. The effects of emodin were found to be similar to that of glybenclamide but different from that of Ba2+ and TEA. The results suggest that the mechanism of action of emodin is to inhibit the activity of KATP channel in the guinea pig taenia coli smooth muscle cells.