Observations on respiratory pigments in slices of avian salt gland and rat liver I. Effects of inhibitors and uncouplers

Abstract

Summary 1. Spectrophotometry and fluorometric techniques have been applied to a study of respiratory pigments in slices of avian salt gland and rat liver. The effects of inhibitors were examined in slices utilising only endogenous substrate. 2. Anaerobiosis and terminal respiratory inhibitors caused a reduction of all the pigments examined. Titration of pigment reduction against O 2 concentration showed that, in salt-gland slices, reduction first started when the p O 2 of the incubation medium was about 0.7 atm. 3. Amytal induced a reduction of pyridine nucleotides, but to a smaller extent than did anaerobiosis; this reduction was inhibited by dicoumarol in rat-liver slices, but not in rat kidney-cortex slices. Amytal caused little change in the level of reduction of cytochromes, apparently due to the presence of endogenous succinate. 4. Malonate induced oxidation of pyridine nucleotides as well as of cytochromes. 5. Dicoumarol revealed a “crossover point” between cytochromes b and ( c plus c 1 ) in salt-gland slices. It caused a small reduction of pyridine nucleotides, apparently due to the stimulation of glycolysis. 6. Iodoacetate induced a biphasic response of the pyridine nucleotides, an initial, transient reduction being followed by a net oxidation. 7. While most of the results are readily explicable in terms of the known effects of the various agents on sub-cellular systems, some cannot be so explained and are apparently due to conditions peculiar to the slices.