Caffeine pre-treatment abolished the genotype difference in severity of ET-1 induced cerebral infarcts. Mice were injected with the adenosine receptor antagonist caffeine (25 mg/kg, i.p.) 30 minutes prior to intracerebral injection of ET-1. A. Ipsilateral CBF was decreased to less than 20% in both Tg and Wt mice; contralateral CBF was decreased by less than 20% at 4 hours post ET-1 injection. B . At 48 hours post ET-1 injection, partial recovery of ipsilateral CBF and full recovery of contralateral CBF was evident. C . Ischemic infarct size, determined 48 hours after ET-1 injection was similar in Tg and Wt mice. Data are means ± SEM; n = 10 Tg, 10 Wt mice.