Angiotensin Converting EnzymeInhibitors Attenuate Ischemic BrainMetabolism inHypertensive Rats

Background andPurpose: Angiotensin converting enzyme (ACE)inhibitors are expected tomodulate neuronal activities. Thepresent study was designed toexamine thebeneficial effects ofACE inhibitors on microcirculation andmetabolism intheischemic brain. Methods: Cerebral ischemia was developed for60minutes inspontaneously hypertensive rats(SHR, n=35)bybilateral carotid artery occlusion. ACEinhibitors (0.1 or10mg/kgSQ29,852 orcaptopril) were intravenously injected 15minutes before cerebral ischemia. Cerebral blood flow totheparietal cortex was measured withtheH2clearance technique. Lactate, pyruvate, andATPinthebrain wereestimated bythe enzymatic method. Results: Before cerebral ischemia, highdoses ofbothSQ29,852 andcaptopril significantly decreased mean arterial pressureby15to25mm Hgandreduced cerebral vascular resistance by13%to17%ofthe resting values. Cerebral blood flowandarterial pressureduring ischemia were notaltered bythese ACE inhibitors. After 60minutes ofcerebral ischemia, tissue lactate invehicle-treated SHRincreased 6.6-fold andATPdecreased to65%ofthecontrol values. Administration ofSQ29,852 orcaptopril significantly reduced thelactate levels to1.6- to3.1-fold andwell preserved theATPlevels to82%to93%ofthecontrol. Conclusions: Theseresults suggest thatinhibition ofACE activities may beprotective forcerebral metabolism against ischemic insult. (Stroke. 1993;24:1561-1567.)