Polarographic and electrophysiological studies of retinal respiration

Abstract

Measurement of the trans- and intraretinal pO 2 by means of oxygen macro- and microelectrodes, were carried out on the isolated retina of fishes ( Eugerres plumieri and Centropomus undecimalis). A difference of 15–20 per cent was found between the pO 2 at the receptor surface, exposed to the gas phase, and the inner surface of the retina, and interpreted as due to oxygen consumption. The O 2 gradient was more marked in the outer retinal layers. Exposure of the retina to 2.5% CO 2 in O 2 accelerated. whereas at 5 per cent it decelerated the retinal respiration. Flash light stimuli on a restricted area of the retina increases the local oxygen consumption. On the other hand, exposure of the retina to ammonia, azide, cyanide or to a gas mixture of CO:O 2 (85:15 per cent) inhibited to a great extent the retinal respiration. The inhibitory effect of carbon monoxide was counteracted by light. The light induced changes in trans- and intraretinal pO 2 obtained from the retinal tissue under exposure to the gas mixture of carbon monoxide and oxygen, were maximal at 425 nm (Soret band), 542 and 590 nm, in correspondance with the peaks of the photochemical action spectrum of Warburg's “Atmungsferment” exposed to CO, indicating that cytochrome oxidase binds with CO in darkness. The changes of the retinal pO 2 were found to correspond with changes in the membrane potential behavior of retinal horizontal cells.