Objective: To study the anti-bradycardic mechanism of Ganfu granule in rats. Methods: The bradycardic model in rats was induced by propranolol (Pro). the activity of glutathione peroxidase(GSH-PX)

superoxide dismutase (SOD) and the content of Malonydialdehyde (MDA) in heart tissue were detected; the content of cyclic adenosine monophosphate (cAMP)

cyclic guanosine monophosphate (cGMP) in heart tissue as well as the content of calcitonin gene-related peptide (CGRP)

endothelin (ET) in plasma were detected by radioimmunoassay. Results: Ganfu granule (30

90

270 mg·kg-1) significantly inhibited the Pro-induced decrease of heart rate in rats

reduced the content of MDA

cGMP in heart tissue

markedly increased the content of CGRP in plasma and the ratio of cAMP/cGMP in heart tissue. Gan granule(90

270 mg·kg-1) markedly increased the activity of SOD and GSH-PX in heart tissue; Compare with model group

the changes of the content of ET in plasma and cAMP in heart tissue were not obviouse. Conclusion: The anti-bradycardic mechanism of Ganfu granule may be related to anti-free radicals

increasing CGRP

regulating the balance between cAMP and cGMP.