With an in-vivo autoradiographic method the binding of 3H-nimodipine (CAS 66085-59-4) and cerebral blood flow (14C-iodoantipyrine method) were measured in rat brain after occlusion of the middle cerebral and common carotid arteries. The dependence of the binding to neuronal cellular membranes on the duration of ischemia can be interpreted as indicator of the tissue's functional state or its responsiveness to therapy with calcium entry blockers. In the two analyzed structures, dorsolateral caudate and overlying sensorimotor cortex, the appearance of infarction is preceded by an activation of the nimodipine binding sites followed by persistent decline of the binding intensity. Binding to nimodipine may therefore be a useful marker of ischemic but salvageable brain tissue.