Iodoacetate poisoning of the rat retina. II. Glycolysis in the poisoned retina.

REPEATED intravenous injections of sodium iodoacetate produce a characteristic visual cell degeneration in the monkey, cat, and rabbit (Schubert and Bornschein, 1951; Noell, 1952), the resulting histological picture being very similar to that presented in human retinitis pigmentosa (Noell, 1953). Recently, it has been shown that a similar condition can be produced in the rat by careful injection of two doses of 30 mg. iodoacetate per kg. body weight, an interval of 4 to 5 hrs being allowed between the two injections (Graymore and Tansley, 1958a). Simultaneous administration of sodium malate was shown to decrease the mortality rate of animals treated in this manner, and yet increase the severity of the visual cell damage. In this way it is possible to obtain experimental animals in which the visual cell population is almost completely destroyed. As early as 1924, Warburg and his associates suggested that all the elements of the retina may not make an equal contribution to the general biochemical picture (Warburg, Posener, and Negelein, 1924) and since then there have been indications that the nerve and receptor components may possess essentially different patterns of metabolism (Noell, 1952; Sjostrand, 1953; Strominger and Lowry, 1955; Lowry, Roberts, and Lewis, 1956). Noell (1952), on the basis of the differing effects of anoxia and iodoacetate on the electroretinogram of rabbits, believed that iodoacetate acted on some mechanism which was not dependent on oxygen, and suggested that the specific action of this substance on the visual cells might be due to the fact that these cells possessed a predominantly glycolytic form of metabolism. It was felt that a study of glycolysis in retinae from rats treated in the manner described above might help to elucidate both the mechanism of action of iodoacetate on the retina as well as certain aspects of the differential metabolism of this tissue. A preliminary report of part of this work has been published elsewhere (Graymore and Tansley, 1958b).