—A significant increase in the retinal ATP content of anaesthetised rats was found 6 days after administration of β, β′-iminodipropionitrile (IDPN). With the development of retinal dystrophy variable ATP levels were observed from the 8th to the 12th day and low values were recorded on the 17th and 21st days.

At 8 days after IDPN administration the ATP content of anaesthetised rat brain was significantly increased with slight decreases in ADP and AMP levels.

The differences in the level of these adenine nucleotides in unanaesthetised and anaesthetised rat brain were not significant before or after IDPN administration.

These results were related to previous experiments on the action of IDPN on the electroretinal response and the later development of a retinal microangiopathy. It was suggested that IDPN has a primary neurotoxic effect followed by the development of vascular morphological changes.