[Study on effect of emodin on the isolated intestinal smooth muscle of guinea-pigs]

Emodin is an active principle of Rheum palmatum. It is reported that emodin possesses antibiotic and antineoplastic functions. The effect of emodin action on the isolated intestinal smooth muscle of guinea-pigs were dose dependent. When the dose of emodin was less than 29.6 mumol/L, the contraction effect enhanced obviously with increasing dosage; but whenever the dose increased to more than 29.6 mumol/L, on the contrary, the effect decreased gradually and ceased finally. Emodin with appropriate concentration (14.8 mumol/L) strengthened the effect of acetylcholine (Ach) on the isolated ileum and large intestine of guinea-pigs (P < 0.05 and P < 0.01). But high concentration of emodin could reduce even completely antagonize the effect of Ach. Under such condition, CaCl2 could restore the effect of Ach on the smooth muscle. It is suggested that emodin has biphasic regulatory effect on the intestinal smooth muscle, and its effect is related to calcium ion.