Microvessels were isolated by albumin flotation and glass bead filtration from cerebral cortices of gerbils decapitated during pentylenetetrazol (PTZ)-induced seizures and ischemia-induced seizures. The uptake of 2-deoxy-D-glucose (2-DG) into these microvessels was studied in vitro. This uptake was increased during PTZ-induced seizures, in keeping with mechanisms whereby glucose transport into brain is increased to keep pace with the augmented tissue glycolysis provoked by enhanced neuronal activity. Uptake of 2-DG was decreased in microvessels isolated from animals that were decapitated while undergoing a seizure during ischemia and 90 to 120 minutes after ischemia. In contrast to results obtained when seizures are due to other causes, these results suggest that brain glucose transport is decreased during a seizure if the microvasculature has been previously subjected to ischemia. The results are discussed in relation to clinical stroke and Todd's postepileptic paralysis.