Differential bioenergetic behavior of in vitro capillary and venule vascular systems. Panel A: Glucose consumed versus lactate produced over time in capillary and venule modules. Note the significant difference between the glucose consumption and lactate production ratio (R) in the capillary module (R≅1) and in the venule (R≅1.5). This indicates that in contrast to venule segments, the brain capillary cellular elements have increased propensity towards the use of aerobic-based glucose metabolism. The asterisk “*” indicates a statistically significant difference (n=4; p<0.05) versus parallel systems established under static conditions.