Deterioration of baroreceptor reflex by transient global cerebral ischemia in dogs

Influence of transient global cerebral ischemia on baroreceptor reflex sensitivity (BRS) was investigated in anesthetized dogs. Cerebral ischemia was produced by the combined occlusions of the left subclavian (LSA) and the brachiocephalic (BCA) arteries with preceding ligations of the intercostal arteries (ICA). BRS was assessed by phenylephrine-induced reflex bradycardia. Ischemia of 5- and 10-min duration produced a significant decrease in BRS during the reperfusion period of 60-120 min. On the other hand, such a change was not observed following the ischemia of less than 2-min or occlusions of LSA and BCA without preceding ligations of ICA. Heart rate response to the electrical stimulation of the vagal afferent nerve was attenuated by 10-min ischemia, while response to the vagal efferent nerve stimulation and ECG parameters were not influenced. These results indicate that some regions vulnerable to the relatively short duration of cerebral ischemia may be involved in the central pathway of the baroreflex mechanism.