Collective effect of a Chinese formula--a study of xiao-jian-zhong-tang.

Components of a traditional Chinese medicine formula Xiao-Jian-Zhong-Tang were divided into three groups: (1) Radix Paeoniae Lactiflorae, (2) Radix Astragali, and (3) Cinnamon twig, Radix Glycyrrhizae, Fructus jujubae and Saccharum Granorum. Extracts of each group were injected into rats to observe the blood pressure wave spectrum changes at the caudate artery. The whole formula was also extracted and injected into rats to monitor blood pressure wave spectrum changes. Each group has its own effect on the Fourier components of the blood pressure wave. The meridian effects of these herbs are the same as described in the Chinese medical literature, if we consider each meridian in resonance with a specific Fourier component. The whole formula when injected into rats had an effect on the Fourier components of the blood pressure wave similar to the linear combination of individual effect of the three herb groups when used separately. This may be the fundamental idea behind formula construction.