BACKGROUND: By detecting vasoactive substances of experimental rats with myocardial ischemia, pharmacological mechanism of xiongbitong was studied in this research.OBJECTIVE: To observe the effect of xiongbitong capsule on release of vasoactive substances of rats with myocardial ischemia.DESIGN: A completely randomized controlled study.SETTING: Department of Health, Weifang Medical College; Department of Physiology, Department of Immunity and Pathogenic Biology, Department of Internal Medicine, Weifang College of Traditional Chinese Medicine.MATERIALS: The experiment had been carried out in the Laboratory of Physiology of Weifang Medical College from January 2003 to June 2003.The cleansing grade 30 Wistar rats, 6-8 months, of either sex, were randomly divided into three groups:namely, normal control group, model control group and model group of treatment with xiongbitong capsule.METHODS: [1] At 12 hours before making model, rats of model treatment group were irrigated with xiongbitong capsule 2.5 g/kg (a capsule contents dried medicinal herbs 1 g), which consists of tuckahoe, rhizoma, immature bitter orange, exocarpium citri grandis, rhizoma acori tatarinowi, moxibustion, dalbergia wood, mongolian snakegourd, curcuma root, red sage root,root of donopsis pilosula, ilyturf root, ophiopogon, polygala root, date kernel etc., and dissolved in 4 mL physiological saline. AT ten hours after making model, they were irrigated with same dose once more. The rats of normal control group and model control group were irrigated with the same dose physiological saline at the same time. One hour after the first irrigation, the animal models of myocardial ischemia of rats of model control group and model treatment group were established by injecting vitriol isoprenaline according to 10 mg/kg subcutaneously. [2] Endothelin (ET), calcitonin generelates peptide (CGRP), 6-keto-prostaglandin Fl alpha (6-keto-PGF1α) and thromboxane B2 (TXB2) in the plasma of rats were detected according to the explanation of Institute of Beijing East Asia Immune Technique. [3] The analysis of variance and q test were used for comparing between groups.MAIN OUTCOME MEASURES: Contents of vasoactive substances in the plasma of rats in each experimental group.RESULTS: The date of all thirty rats was entered the final analysis. [1]The contents of (TXB2) and ET, TXB2/6-Keto-PGF1α, ET/CGRP: Compared with the model group, the normal control group and model treatment group reduced obviously (q=2.99-9.87, P ＜ 0.05-0.01). [2] The contents of 6-Ke-to-PGF1α and CGRP: Compared with the model group, the normal control group and model treatment group increased obviously [(603.3 ±90.6),(190.0±64.2) ng/L; (560.7±111.1), (174.9±41.4) ng/L; (380.4±705),(114.9±36.4) ng/L, q=3.88-7.64, P ＜ 0.05-0.01].CONCLUSION: Xiongbitong capsule may suppress unusual release of vasoactive material at myocardial ischemia area obviously, increase the content of expanding the blood vessel material, and correct out-of-balance of content of important TXB2, 6-keto-PGF1α, XTB and CGRP in the body.