Effect of shakuyaku-kanzoh-toh, a prescription composed of shakuyaku (Paeoniae Radix) and kanzoh (Glycyrrhizae Radix) on guinea pig ileum.

The actions of shakuyaku-kanzoh-toh (SK), a prescription of the traditional Chinese medicine, on an isolated guinea pig ileum were studied by comparing those of shakuyaku (S) (peony root, Paeoniae Radix) and kanzoh (K) (licorice root, Glycyrrhizae Radix). SK, S and K suppressed the neurogenic contractions of ileum induced by electrical stimulation and ganglionic stimulating agents such as DMPP and nicotine. Although S did not influence acetylcholine (ACh)-induced contraction of ileum, K inhibited ACh-induced contraction to the same extent as the neurogenic contraction. Also SK inhibited ACh-induced contraction but its inhibition was smaller than the inhibition of the neurogenic contraction. SK and K inhibited 40 mM KCl-induced contraction of ileum and the specific binding of 3H-QNB on muscarinic receptors in ileum, but S at 3 X 10(-4) and 10(-3) g/ml, which were enough to suppress the neurogenic contraction of ileum, did not inhibit them. These results suggest that the inhibitory actions of S and K on the neurogenic contraction are due to an inhibition of ACh release from cholinergic nerve and an inhibition of ACh action on ileum smooth muscle, respectively, and that the inhibitory actions of SK are responsible for both inhibitions by S and K. The inhibitions of ACh action by SK and K are presumed to be due to inhibitions of ACh binding on muscarinic receptors and of contractile machinery of smooth muscle.