The rate of O2 uptake in cells isolated from the skate gastric mucosa was determined as a function of the ratio [CO]/[O2] by an O2 electrode method. Skate cells are five times less sensitive to the effects of CO than yeast, which was used as a normal control cell. In both cell types, CO inhibition can be partially reversed by white light. Therefore, the action spectrum for the relief of CO inhibition was determined for the two cell types. In yeast, the alpha peak of the action spectrum for photodissociation of the CO-oxidase complex (which is the alpha peak of the absorption spectrum of this complex) is found at 590 nm, as expected from prior work on this oxidase. In skate gastric mucosa cells, the corresponding peak is at 580 nm, and these two peaks clearly represent different CO complexes. These observations help to explain the lack of CO inhibition of acid secretion in the skate gastric mucosa, and the observation of a non-standard terminal oxidase in the absorption spectrum of this tissue.
