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(Stroke. 1998;29:850-858.)
© 1998 American Heart Association, Inc.

Original Contributions

A Novel Endothelin Antagonist, A-127722, Attenuates Ischemic Lesion Size in Rats With Temporary Middle Cerebral Artery Occlusion

A Diffusion and Perfusion MRI Study

Turgut Tatlisumak, MD; Richard A. D. Carano, MS; Kentaro Takano, MD, PhD; Terry J. Opgenorth, PhD; Christopher H. Sotak, PhD; Marc Fisher, MD

From the Department of Neurology, Helsinki University Central Hospital (Finland) (T.T.); Department of Neurology, Medical Center of Central Massachusetts–Memorial (T.T., K.T., M.F.), Department of Biomedical Engineering, Worcester Polytechnic Institute (R.A.D.C., C.H.S.), and Departments of Neurology (T.T., K.T., M.F.) and Radiology (M.F.), University of Massachusetts Medical School, Worcester, Mass; and Abbott Laboratories, Abbott Park, Ill (T.J.O.).

Correspondence to Dr Turgut Tatlisumak, Department of Neurology, Helsinki University Central Hospital, Haartmaninkatu 4, FIN-00290 Helsinki, Finland. E-mail turgut.tatlisumak{at}helsinki.fi

Background and Purpose—Endothelins (ETs) are potent vasoconstrictors. Plasma ET levels increase during acute brain ischemia and may worsen the ischemic damage. Diffusion-weighted MRI (DWI) and perfusion imaging (PI) are powerful tools for evaluation of acute cerebral ischemia. We studied the effects of A-127722, a novel ET_A-selective ET antagonist, on cerebral ischemic lesion size using 2,3,5-triphenyltetrazolium chloride (TTC) staining postmortem, on acute ischemic lesion development with DWI, and on the cerebral circulation using PI.

Methods—Twenty male Sprague-Dawley rats received either 5 mg/kg of A-127722 or vehicle (n=10 per group) intravenously 30 minutes and subcutaneously 4 hours after middle cerebral artery occlusion (MCAO). Whole-brain DWI and single-slice PI were done before initiation of treatment and repeated frequently thereafter up to 4 hours after MCAO. The animals were reperfused in the MRI scanner 90 minutes after the onset of MCAO. At 24 hours the animals were killed, and the brains were cut into six 2-mm-thick slices and stained with 2% TTC. Percent hemispheric lesion volume (%HLV) was calculated for each animal.

Results—Physiological parameters, body weight, neurological scores, and premature mortality (2 versus 2) did not differ between the two groups. No hypotension, abnormal behavior, or other adverse effects were seen. TTC-derived %HLV was 25.3±5.6% for controls and 16.2±9.6% for treated animals (36% reduction, P<.02). Six animals in each group had successful reperfusion as shown by PI. Among these animals, %HLV was 23.2±3.1% for controls and 9.3±4.4% for treated animals (60% reduction, P=.0001). The beneficial effect of A-127722 was limited to animals in which successful reperfusion was demonstrated. No difference in PI-detected perfusion deficit size was observed between the groups. DWI did not demonstrate significant in vivo lesion size differences.

Conclusions—A-127722 significantly reduced ischemic lesion size in rats without observable adverse effects. It is not clear whether the effect was due to vasodilatation of collateral arterioles not detectable by PI or whether A-127722 has neuroprotective properties that are independent of vascular effects.

Editorial Comment

A Diffusion and Perfusion MRI Study

Chung Y. Hsu, MD, PhD; Weili Lin, PhD, Guest Editors

Department of Neurology and, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri

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