Abstract
Further studies of the retinal glutamate effect have shown that not only is glutaminase I decreased in glutamate-treated rat retinas, but glutamic-aspartic transaminase is significantly increased. Direct competitive inhibition of glutaminase I by glutamate can be demonstrated. However, studies with labeled glutamate show that under the conditions of our experiments, retinal concentrations of glutamate reach, at most, the 10 per cent inhibitory level, and that for only a short time. This increases the likelihood, that the observed, effects are due to repression and induction of enzyme synthesis.