Cerebral and cerebellar blood flow autoregulations in acutely induced cerebral ischemia in spontaneously hypertensive rats--transtentorial remote effect.

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Abstract
Autoregulation of cerebral (CBF) and cerebellar blood flow (CeBF) was studied before, during and after acutely induced cerebral ischemia in spontaneously hypertensive rats. Cerebral ischemia of the supratentorial portion was induced for one hour by bilateral carotid artery ligation (BCL). The animals were artificially ventilated and the blood flow was measured with a hydrogen clearance technique. To test the autoregulation, the blood pressure was stepwise lowered by bleeding and maintained at a new level, i.e. 15% or 30% lower than the baseline values before, during and after cerebral ischemia. At the preischemic state, CBF and CeBF were 52.1 +/- 6.2 and 58.9 +/- 4.6 ml/100 g/min (mean +/- SEM), of which autoregulations were normally preserved. Following BCL, CBF was markedly decreased to about 10% of control value while CeBF was minimally reduced to 46.9 +/- 8.6 ml/100 g/min (80%). At the ischemic state, CBF became almost zero flow during hypotension. CeBF was also reduced to 74% and further to 58% of th...