THE METABOLISM OF THE KIDNEY IN EXPERIMENTAL RENAL HYPERTENSION : II. THE CONCENTRATION OF CYTOCHROME C AND THE ACTIVITIES OF THE CYTOCHROME OXIDASE AND OF THE SUCCINIC DEHYDROGENASE SYSTEMS IN THE KIDNEY OF DOGS WITH EXPERIMENTAL RENAL HYPERTENSION. THE INHIBITORY EFFECT OF RENIN AND OF KIDNEY TISSUE PREPARATIONS FROM HYPERTENSIVE DOGS ON THE RESPIRATORY ENZYMES.

These investigations are part of an attempt to study and interpret the intermediary metabolism of the kidneys in experimental renal hypertension. Hypertension was produced in dogs by the clamping procedure of Goldblatt and associates or by the silk perinephritis method of Page. Enzymatic studies were made by means of Warburg's manometric method. Cytochrome c was in addition determined spectrophotometrically. Tissue slices, homogenized tissue, and tissue extracts were used. A study of the cytochrome c concentration and the activities of the cytochrome oxidase and succinic dehydrogenase systems of kidneys from normal dogs and dogs with experimental renal hypertension was made. It was found that the cytochrome c concentration and the activities of the cytochrome oxidase and succinic dehydrogenase systems were markedly lower in the kidney slices and in the tissue suspensions from hypertensive dogs. Tissue suspensions and extracts of kidneys from hypertensive dogs showed an inhibitory effect on the activity of the cytochrome oxidase and succinic dehydrogenase, and the amine oxidase systems. Renin preparations also showed a marked inhibitory effect on the activities of cytochrome oxidase, succinic dehydrogenase, l-amino acid oxidase, and amine oxidase systems. A significant increase was found in the kidney of dogs whose other kidney had been removed or subjected to Goldblatt's or Page's technique in the activities of the cytochrome-cytochrome oxidase system, the succinic dehydrogenase system, and in the concentration of nucleotide-bound phosphorus, of flavin-adenine dinucleotide, and of the nicotinamide-adenine dinucleotides (coenzymes I and II). From the results of these studies it can be concluded that an increase in the concentration and activity of the respiratory enzymes precedes hypertrophy of the kidney. This can be explained by the assumption that an increase in the activity of the respiratory biocatalysts acts as a stimulus for cell growth and multiplication.