Abstract：Objective：To investigated possible mechanism of relief of angina pectoris treated by transmyocardial laser revascularization. Methods: Models of canine myocardial infarction were established by ligation of left anterior descending artery and injection of air embolism into distal end to the ligation. All animals were divided randomly into treated (n=6) and control group (n=6). Four weeks after the first operation, twenty transmyocardial revascularization channels were placed in ischemic sites on the hearts of treated group and sham operation in control group. Eight weeks after the first operation, blood sample was collected rapidly from the great coronary vein and centrifuged at 4 ℃ before and after dobutamine stress，the plasma obtained was directly submitted to radioimmunoassay. Myocardium treated with laser and corresponding site in the control group was excised for detecting mRNA of A1 receptor with semi-quantitative RT-PCR. Results : The levels of great coronary vein adenosine at rest in treated group and control group were 785.0±173.7 and 888.2±273.0 pmol/ml plasma, respectively, without any significant difference between them. Dobutamine stress significantly increased coronary vein adenosine level in control group from 888.2±273.0 to 1273.0±247.1 pmol/ml plasma, with significance difference between them (p<0.05). In treated group, the content of adenosine increase mildly from 785.0±173.7 to 950.8±223.0 pmol/ml plasma, no significant difference was found (p>0.05) between them. Relative integral optical density of mRNA of A1 receptor in treated group (0.39±0.09) was comparable to control group (0.40±0.19). Conclusion: The level of adenosine in treated group was lower significantly than that in control group during dobutamine stress which may be the mechanism of relief of angina pectoris.