Effect of intracarotid bradykinin infusion on cerebral blood flow in dogs

We examined whether intracarotid infusion of bradykinin altered circulation in the normal canine brain. Twenty-four anesthetized dogs were divided into four groups receiving different doses of bradykinin (1, 2.5, 5, and 10 μg kg^-1 min^-1). Regional cerebral blood flow (rCBF) was measured continuously using laser Doppler flowmetry through a burr hole in the frontal bone. Systemic blood pressure (SBP) and heart rate (HR) were monitored simultaneously. Higher doses of bradykinin significantly but temporarily decreased rCBF and SBP immediately after the start of infusion; these parameters rapidly recovered and then were stable through the rest of the infusion. During this period, percent change in rCBF and SBP was small, and differences between groups were not significant. On the other hand, HR increased during infusion and remained high. SBP, rCBF, and HR returned to pre-infusion levels after bradykinin was stopped. The results suggest that intracarotid infusion of bradykinin for treatment of brain tumors would be safe in terms of circulation to the uninvolved brain.