Introduction-Cerebral vasoconstriction is associated with increased cytosolic Ca 2+ concentration in vascular smooth muscle, presumably due to Ca 2+ influx and Ca 2+ release from intracellular stores. We tested the hypothesis that dantrolene (a blocker of Ca 2+ -induced Ca 2+ release from the ryanodine receptor channel on the sarco-endoplasmic reticulum) would potentiate the action of nimodipine (a voltage-dependent L-type Ca 2+ channel blocker, considered standard therapy for SAH) in inhibiting the vasoconstriction of isolated cerebral arteries.

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.

Background: Rho-associated kinases (ROCK1 and ROCK2) are important regulators of the actin cytoskeleton and endothelial nitric oxide synthase (eNOS). Because the phosphorylation of eukaryotic elongation factor-1 A1 (eEF1 A1) by ROCK2 is critical for eNOS expression, we hypothesized that this molecular pathway may play a critical role in neuroprotection following focal cerebral ischemia. Methods and Results: Adult male wild-type (WT) and mutant ROCK2 and eNOS−/− mice were subjected to middle cerebral artery occlusion (MCAO), and cerebral infarct size, neurological deficit and absolute cerebral blood flow were measured. In addition, aortic endothelium-dependent response to acetylcholine, NG-nitro-L-arginine methyl ester (L-NAME) and sodium nitroprusside were assessed ex vivo. Endothelial cells from mouse brain or heart were used to measure eNOS and eEF1A activity, as well as NO production and eNOS mRNA half-life. In global hemizygous ROCK2+/− and endothelial-specific EC-ROCK2−/− mice, eNOS mRNA stability and eNOS expression were increased, which correlated with enhanced endothelium-dependent relaxation and neuroprotection following focal cerebral ischemia. Indeed, when ROCK2+/− mice were place on an eNOS−/− background, the neuroprotective effects observed in ROCK2+/− mice were abolished. Conclusions: These findings indicate that the phosphorylation of eEF1A1 by ROCK2 is physiologically important for eNOS expression and NO-mediated neuroprotection, and suggest that targeting endothelial ROCK2 and eEF1A may have therapeutic benefits in ischemic stroke and cardiovascular disease.