Ras protein contributes to cerebral vasospasm in a canine double-hemorrhage model

Background and Purpose-Mitogen-activated protein kinase ( MAPK) has been shown to be involved in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). In the present study we examined the role of Ras protein, an upstream regulator of MAPK, and the effects of the inhibitors of Ras farnesyltransferase (FTase), FTI-277 and FTase inhibitor I, on angiographic vasospasm and clinical evaluations. Methods-Twenty-five dogs were randomly divided into 5 groups: control, SAH, SAH+dimethyl sulfoxide, SAH+FTI-277, and SAH+FTase inhibitor I. An established canine double-hemorrhage model of SAH was used by injecting autologous arterial blood into the cisterna magna on days 0 and 2. Angiography was performed at days 0 and 7. Clinical behavior and the activation of Ras (GTP-Ras) and phosphorylated ERK1/2 of MAPK in the basilar arteries were examined. Results-Severe vasospasm was obtained in the SAH and SAH+dimethyl sulfoxide dogs (42.5+/-2.5% and 38.9+/-2.4%, respectively). Enhanced GTP-Ras and phosphorylated ERK1/2 were observed in the spastic basilar arteries (P<0.05). Inhibitors of Ras FTase decreased GTP-Ras and phosphorylated ERK1/2, attenuated angiographic vasospasm, and improved appetite and activity scores. Conclusions-Ras contributes to cerebral vasospasm, and inhibitors of Ras FTase may have potential in the management of cerebral vasospasm.