We report here that cortisol induction of glutamine synthetase in the chick embryo retina is maximal when the glucose concentration in the culture medium is 0.2 g/1, rather than the 1 g/1 (0.1%, or 6 mM) customarily found in many commercially available media; induction is a factor of 2.1 higher at 0.2 g/1. Glutamine synthetase is known to be localized within retinal Müller cells. The pH of the medium at the end of a 24-hr culture period is generally higher (approximately 7.2) in the low-glucose medium than that found in the standard maintenance medium (pH approximately 6.8), probably indicating decreased metabolism at the lower sugar concentration. Manipulation of the culture medium components may provide a method to monitor metabolic stress responses of Müller cells.