Calcium antagonist isradipine reduces metabolic alterations in acute cerebral ischemia in spontaneously hypertensive rats

The present study was designed to examine the effect of a calcium antagonis t isradipine (PN200-110: PN) on local cerebral blood flow and brain tissue metabolism after 1-hour supratentorial ischemia induced by bilateral caroti d artery ligation (BCL) in spontaneously hypertensive rats (SHR). PN, disso lved in ethanol plus polyethylene glycol 400, diluted with saline to make t he final concentration of 0.25mg/ml and 2.5mg/ml, was administered subcutan eously either 30 min prior to BCL or just after the induction of incomplete cerebral ischemia (n = 7 in each group). Vehicle injection was served as a control group (n = 7). Cerebral blood flow in the parietal cortex (CBF) an d the cerebellar cortex (CeBF) was measured by hydrogen clearance technique , and the supra- and infratentorial metabolites of the brain frozen in situ were determined by the enzymatic method. Blood pressure was lowered, but C BF was increased by PN administration in pre-BCL treatment study. After 1 h our of BCL, CBF decreased to around 10% or less of the resting value, being insignificant among the groups. Brain adenosine triphosphate was better pr eserved in PN-administered groups. The increase in lactate level tended to reduce dose dependently by PN treatment. PN also reduced the metabolic alte rations in brain tissue with significance, even when administered just afte r the induction of forebrain ischemia. It is considered that pre- as well a s post-BCL administration of PN is beneficial to attenuate the metabolic al terations in incomplete forebrain ischemia in SHR.