BACKGROUND: Pharmacologic action of traditional Chinese medicine compound is the comprehensive effect of various ingredients, and the interactions of various ingredients are closely correlated with the final effect. In order to reveal the compatibility mechanism of buyang huanwu decoction (BHD)s prescription in treating and preventing ischemic cerebrovascular disease, we need to explore the effect and relation of ingredients in prescription except for considering the effect of each ingredient on the whole prescription.OBJECTIVE: To study the effect of BHD and its ingredients in the prescription on the specific binding of 3H-platelet activating factor (PAF) to its receptor (PAFR)in rabbits in vitro, and to analyze the action of each ingredient in the prescription.DESIGN: A decomposed recipe study based on orthogonal test.SETTING: Guangzhou University of Traditional Chinese Medicine.MATERIALS: Five healthy adult New Zealand rabbits of either gender were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese medicine. The prescription herbal pieces were purchased from Foshan Kangpu Pharmaceuticals Company and Jianmin Pharmaceuticals Company, and were appraised by Professor Yanchen Xu from College of Traditional Chinese Medicine, Guangzhou University of Traditional Chinese Medicine. 3H-PAF was supplied by Amersham Co.,Ltd.(Specific activity:6.475 TBq/mmol;batch number:200402); PAF standard by Biomol Co., Ltd.(batch number: P1318V).METHODS: This experiment was carried out in the Laboratory of Nuclear Medicine, Guangzhou University of Traditional Chinese Medicine between September and December 2004. ① The seven influencing factors were selected: such as Shenghuangqi , Dangguiwei, Chishao, Dilong, Taoren, Honghua, Chuanxiong. Each factor was divided into two levels, selected or not selected. The tests were arranged according to L8 (27) orthogonal test table. ②The specific binding of 3H-PAF to its receptors in rabbits was measured by radioligand binding assay. The inhibitory rate of the specific binding was used as an assessing index. The inhibitory action of and on 3H-PAF to PAFR binding was analyzed and compared in vitro. The inhibitory action of each ingredient in the prescription BHD·on 3H-PAF to PAFR binding was investigated and compared in vitro by direct analysis and analysis of variance of orthogonal test.MAIN OUTCOME MEASURES: Effect of 8 prescriptions for L8 (27) orthogonal test table on the specific binding inhibition rate of 3H-PAF and PAFR.RESULTS: According to results of variance analysis of orthogonal test, the inhibitory action of each ingredient in the prescription BHD on 3H-PAF to PAFR binding from the highest to the lowest was in turn Honghua, Shenghuangqi, Taoren, Dilong, Dangguiwei, Chuanxiong, Chishao. Honghua, Shenghuangqi,Taoren, Dilong, Danguiwei were major influence factors to 3H-PAF to PAFR in rabbits (F =187.829,144.446,59.521,5.018,4.265, P ＜ 0.05- 0.01), but Chuanxiong and Chishao had not obviously inhibitory effect. The specific binding inhibition rate of prescriptions (except Shenghuangqi ) was obviously higher than that of one of prescriptions (Shenghuangqi included).CONCLUSION: The results of orthogonal test show that Honghua, Shenghuangqi, Taoren, Dilong,Dangguiwei are major influencing factors to inhibit binding of 3H-PAF to PAFR in rabbits, among which,Honghua is the strongest in ingredients of prescription BHD. The results also reveal that Shenghuangqi is able to weaken the inhibitory effect and to prevent the strong inhibitory effect of blood-activating drugs in BHD.