ABSTRACT
Carbadox is known to induce toxic effects on the adrenal cortex, resulting in hypoaldosteronism. To study the involvement of carbadox on the renin-angiotensin system, weaned piglets of five weeks old received feed supplemented with 0 (control group), 50, 100, 150 or 200 ppm carbadox. After four weeks the 100 and 150 ppm groups had significantly higher plasma renin activity levels than the control group and after nine weeks plasma renin activity levels of all treated groups were significantly higher than the control group. Five and 10 weeks after carbadox administration, three and two pigs, respectively, of all groups were necropsied and the kidneys were screened for immunohistochemically demonstrated renin. All dosed pigs demonstrated an increase of immunoreactive renin, which was dose- and time-related. From these results it is concluded that carbadox induces activation of the renin-angiotensin system, secondary to the suppressing effect on mineralocorticoid secretion and that these changes may be responsible for part of the clinical picture.
Subject(s)
Carbadox/administration & dosage , Kidney/analysis , Quinoxalines/administration & dosage , Renin/analysis , Swine/metabolism , Administration, Oral , Animals , Carbadox/poisoning , Renin/blood , Renin-Angiotensin System/drug effectsABSTRACT
The ultrastructural localization of renin in the juxtaglomerular apparatus of the kidney of the toad Bufo bufo has been examined using an immunogold staining method for electron microscopic immunocytochemistry and an antiserum to renin isolated from the submandibular gland of the mouse. Renin immunoreactivity was confined to lamellated granules in the cytoplasm of epitheloid or juxtaglomerular cells in the glomerular afferent arterioles and also in the media cells of larger arteries. Mouse kidney tissue, examined for purposes of comparison, showed immunolabeling limited to the granules of the juxtaglomerular cells. The presence of renin or a renin-like substance in the juxtaglomerular granules of the toad kidney is discussed in relation to the lysosomal nature of these granules. A model is presented linking the lysosomal function of the juxtaglomerular granules and the release of renin mediated by beta-adrenergic receptors present on the surface of the juxtaglomerular cells.
Subject(s)
Bufo bufo/metabolism , Juxtaglomerular Apparatus/analysis , Renin/analysis , Animals , Cytoplasmic Granules/analysis , Gold , Histocytochemistry , Immunologic Techniques , Juxtaglomerular Apparatus/ultrastructure , Male , Mice , Mice, Inbred C57BL , Microscopy, ElectronABSTRACT
Histochemical techniques for acid phosphatase activity applied to kidney tissue of the toad Bufo bufo demonstrate that a high enzyme activity is present in the dense granules of the proximal tubule cells, but also in the media cells in the wall of the glomerular afferent arterioles. The acid phosphatase activity is confined to the characteristic granules in these juxtaglomerular cells, which therefore are lysosomal in nature.
Subject(s)
Acid Phosphatase/analysis , Bufo bufo/metabolism , Juxtaglomerular Apparatus/enzymology , Animals , Arterioles/enzymology , Arterioles/ultrastructure , Epithelium/enzymology , Epithelium/ultrastructure , Histocytochemistry , Juxtaglomerular Apparatus/blood supply , Kidney Tubules, Proximal/blood supply , Kidney Tubules, Proximal/enzymology , MaleABSTRACT
The cellular localization of renin was examined in the kidneys of some amphibians of the genus Bufo by immunoperoxidase and immunofluorescence techniques with an antiserum to renin isolated from the submandibular gland of the mouse. Immunoreactivity could be demonstrated in the media cells of the afferent arterioles (juxtaglomerular cells) close to as well as at great distance from the glomeruli. Occasionally, media cells of larger arterial vessels were also stained. The immunohistochemical data seem to be in accordance with earlier results obtained with a modified silver impregnation technique (Movat's staining procedure) used for the visualization of juxtaglomerular cells in non-mammalian vertebrates. Mouse kidney tissue, studied for purposes of comparison, showed renin-immunoreactivity as described by earlier investigators, i.e., immunoreactive staining in the afferent arterioles near the glomeruli and in the proximal tubule cells.
Subject(s)
Bufonidae/anatomy & histology , Juxtaglomerular Apparatus/metabolism , Renin/metabolism , Animals , Bufonidae/metabolism , Immunologic Techniques , Juxtaglomerular Apparatus/ultrastructureABSTRACT
An investigation regarding the question of whether there exists a macula densa as part of the juxtaglomerular apparatus in the kidney of amphibians has been carried out. With the aid of a histochemical reaction for glucose-6-phosphate dehydrogenase activity, the presence of a macula densa zone as a specialized part of the distal tubule in the toad Bufo bufo was demonstrated. The functional significance of the high glucose-6-phosphate dehydrogenase activity in the macula densa cells is discussed.
