The influence of short-time cerebral ischemia on pial vessels adrenoreactivity in rats

Abstract

Introduction and purpose. It is known that ischemia influences on endothelial reactions, changes metabolic and myogenic mechanisms of cerebral blood flow regulation. But the role of local neurogenic mechanisms of regulation in change of cerebral vessels reactions after ischemia is finally not found out. The aim of the current study was to examine the pial vessels reactivity in response to a brain surface irrigation by norepinephrine solution in rats, subjected to transient global cerebral ischemia, at 2, 7, 14 and 21 days after ischemia. Materials and methods. Transient global cerebral ischemia was induced in anesthetized Wistar rats by clamping of both common carotid arteries for 12 min with simultaneous controlled hypotension to 45±3 mm Hg, followed by blood reinfusion and recovering from anesthesia. Four different groups of rats were re-anesthetized at 2, 7, 14 or 21 days after ischemia and subjected to microvascular studies using in-vivo video microscopy method. The diameter changes of pial arteries and veins in response to norepinephrine were measured. Results and discussion. It was established that cerebral ischemia led to increase number of the constrictions to norepinephrine mainly at the vessels to relating to group of small pial arteries and arterioles and pial veins of the 3-rd generation. Reactivity changes were observed in all time points studied. This changes probably is connected with caused by ischemia the increase in reactivity and sensitivity of pial vessels adrenoceptors. The greatest changes are noted in 14 days after ischemia. The use of non-selective α-adrenergic antagonist - nicergoline at ischemic and intact rats, led to increase number of the constrictions to norepinephrine. But at ischemic rats decrease was more considerable. And number of dilation reactions to norepinephrine at ischemic rats was also above. It can indicate to increase of adrenoceptors reactivity and sensitivity. Conclusions. Thus, transient global cerebral ischemia cause marked and long lasting (3 weeks) increase in pial vessels reactivity in response to norepinephrine, that is probably connected with increase of adrenoceptors reactivity and sensitivity.