Abstract: Experiment on isolated basilar arteries of dogs showed that ethyl apovincamine-22-oate (Cavinton, CAV), a new cerebral vasodilator, at 10^-6 mol/L could antagonize the contractile effect of high K⁺(40 mmol/L) on the vessels. At lower concentration (10^-6mol/L), CAV was shown to competitively shift the concentration-response curve of 5-HT(0.5～512×10^-8mol/L) to the right, and at higher concentration (10^-5mol/L), the curve was further depressed. This inhibitory effect of CAV to 5-HT and high K⁺ on cerebral vessels may be beneficial in the treatment of ischaemic cerebral vascular diseases. CAV(5 × 10^-6mol/L)caused a transient contraction of the vessels at resting state. This effect was antagonized by promethazine (10^-5mol/L) and pizotifenum (10^-5mol/L).