Choline acetyltransferase activity in chick retina cultures: effect of membrane depolarizing agents

The activity of choline acetyltransferase (CAT) was investigated in primary cultures of retina from 8-day-old chick embryos. After the second day in culture, the total and specific activities of the enzyme decreased by more than 50%. Cultivation of the cells in 56 mM K+ or 59 microgram/ml of veratrine retarded the loss of CAT activity up to days 3-5 in vitro. If the addition of 56 mM K+ or 59 microgram/ml of veratrine was delayed until the third day of culture, these agents had no effect on the remaining CAT activity. These results suggest that the survival in culture of a part of the cholinergic retinal neurons requires membrane depolarization.