Effect of Xingnaokang formula(XNKF)on cerebral tolerance to anoxia was studied in rats and mice.The effects of XNKF on cerebral circulation were also examined by electromagnetic flow meter in dogs.The findings revealed that XNKF(6.0、12.0g/kg ig)significantly prolonged the survival time of the animals with cerebral ischimia anoxia and the lasting time of cerebral electrical activities in rats after their tracheae were blocked XNKF extraction(10.0、20.0g/kg iv)can also dilate the cerebral blood vessels

decrease the resistance of cerebral blood vessels

and increase the flow of cerebral blood in dogs.In the primary period of its action

XNKF extraction can lower the myocardial tension-time index steadily and the blood pressure temporarily

but no effect on heartbeat in dogs.