In this study, we determined whether the retina cell death observed in response to an ischemic-like insult is related to an overactivation of the
ionotropic glutamate receptors and/or to a collapse of the energy levels. Cultured chick retina cells were submitted to 'chemical
ischemia' by metabolic inhibition with
sodium cyanide and
iodoacetic acid, which block oxidative phosphorylation and glycolysis, respectively. The assessment of neuronal injury was made spectrophotometrically by quantification of cellularly reduced MTT, which gives information about mitochondrial function, or by staining with
fluorescein diacetate (FDA), which correlates with changes in the plasma membrane permeability. 'Chemical
ischemia' induced both an acute and a delayed time-dependent degeneration of chick retina cells. We observed that 2 min after the ischemic insult, the levels of
ATP were reduced to a minimum. On the other hand, the metabolic inhibition induced the release of
aspartate,
glutamate and
gamma-aminobutyric acid, and the activation of
AMPA/
kainate receptors during the period of metabolic arrest was partially responsible for the loss of mitochondrial function. However, the
NMDA and non-
NMDA receptor antagonists (
MK-801 and
CNQX) did not prevent the plasma membrane damage caused by
sodium cyanide and
iodoacetic acid. The results show that the collapse of the energy levels, rather than the increase in
excitatory amino acids, appears to underlie the observed cell injury, suggesting an important relationship between
ischemia-induced depletion of high-energy metabolites and retina cell degeneration.