1987 Volume 9 Issue 4 Pages 291-297
Effect of lowering of blood pressure on acutely-induced cerebral ischemia was studied using spontaneously hypertensive rats (SHR). Cerebral ischemia was produced by bilateral common carotid artery ligation (BLCL). Reserpine was administered intraperitoneally for antihypertensive treatment after producing cerebral ischemia. Blood pressure was moniterd and regional blood flow (r-CBF) in the occipital deep brain was measured periodically. Cerebral metabolites (ATP, lactate, c-AMP) and brain water content were also measured 3 hr after the BLCL. They were determined in the frontal and the occipital brain of each hemisphere, because the experimental cerebral ischemia induced by BLCL was severe in the frontal region and was mild in the occipital.
There was a tendency of a decrease in r-CBF by the lowering of blood pressure. Also it was shown that r-CBF had positive correlation to the blood pressure at 3 hr after BLCL. Brain ATP was remarkably decreased in the frontal and the occipital region and brain lactate was markedly accumulated in both regions. c-AMP was not changed remarkably. The ATP levels in the occipital region were reduced in the antihypertensive treated group compared to those in the untreated group. The lactate levels in the occipital region were increased in the treated group compared to those in the untreated group. There was no differences in the c-AMP levels between the treated and the untreated group in the frontal and the occipital regions. The ATP levels in the occipital had positive correlation to the blood pressure at 3 hr after BLCL. The lactate levels in the occipital had negative correlation to the blood pressure, while the c-AMP levels had no correlation to the blood pressure. Brain water content in the frontal and the occipital regions in the treated group was higher than that in the untreated. The brain water content had negative correlation to the blood pressure at 3 hr after BLCL in the frontal and the occipital areas.
It is shown that lowering of blood pressure in cerebral ischemia in the acute stage results in reduction of r-CBF and aggravates cerebral metabolism and brain edema. Also the effect of lowering of blood pressure is more prominent in the occipital region. Therefore hypertension in the acute stage of ischemia should be carefully managed.
