1. ¹Vascular Medicine Research Unit, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
2. ²Stroke and Neurovascular Regulation Laboratory, Department of Neurology and Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA

Correspondence: Dr JK Liao, Vascular Medicine Research Unit, Department of Medicine, Brigham and Women's Hospital, 65 Landsdowne Street, Room 275, Cambridge, MA 02139, USA. E-mail: jliao@rics.bwh.harvard.edu

Received 25 October 2007; Revised 20 February 2008; Accepted 29 February 2008; Published online 2 April 2008.

Abstract

Recent studies suggest that dipyridamole (DP) may exert stroke protective effects beyond platelet inhibition. The purpose of this study is to determine whether statin and DP could enhance stroke protection through nitric oxide (NO)-dependent vascular effects. Mice were pretreated with DP (10 to 60 mg/kg, q 12 h, 3 days) alone or in combination with a statin (simvastatin; 0.1 to 20 mg/kg per day, 14 days) before transient intraluminal middle cerebral artery occlusion. Although simvastatin (1 mg/kg per day, 14 days) increased endothelial NO synthase (eNOS) activity by 25% and DP (30 mg/kg, q12 h, 3 days) increased aortic cGMP levels by 55% , neither statin nor DP alone, at these subtherapeutic doses, increased absolute cerebral blood flow (CBF) or conferred stroke protection. However, the combination of subtherapeutic doses of simvastatin and DP increased CBF by 50% , decreased stroke volume by 54% , and improved neurologic motor deficits, all of which were absent in eNOS-deficient mice. In contrast, treatment with aspirin (10 mg/kg per day, 3 days) did not augment the neuroprotective effects of DP and/or simvastatin. These findings indicate that statin and DP exert additive NO-dependent vascular effects and suggest that the combination of statin and DP has greater benefits in stroke protection than statin alone through vascular protection.