['It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport.', 'Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning.', 'Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel density decreased from the fascial to the tumor surface.'] Do tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model?