Immunohistochemical localization of carbonic anhydrase in postnatal and adult rat kidney

Abstract

With use of specific antibodies against human and rat erythrocyte carbonic anhydrase C and human carbonic anhydrase B, only the isozyme C could be detected by immunofluorescence in rat kidney epithelial cells. In the postnatal kidney a few cells were positive after 2 days, but the number of fluorescent cells increased during the first few weeks of life to reach the final adult levels after 3 wk in the cortex and 5 wk in the medulla. In the postnatal and adult kidney a characteristic mosaic pattern of fluorescence was seen in the late distal tubule, the connecting segment, and the collecting tubule, where the mitochondria-rich dark cells were brightly fluorescent. In addition, in later postnatal stages and in the adult, the entire epithelium of the initial portion of descending thin limbs of Henle (long loops) was labeled. Some kidney regions that had previously been shown to contain carbonic anhydrase activity by biochemical and histochemical techniques stained only weakly with the immunocytochemical method. This suggests either that the enzyme in these regions does not cross-react strongly with our antibodies or that these regions contain only low amounts of carbonic anhydrase, at the limit of the detection threshold of our techniques.

Expression of protein kinase C isoenzymes α, βI, and δ in subtypes of intercalated cells of mouse kidney

“…Intercalated cells are subclassified into type A, type B, and non-A-non-B cells based on the presence or absence of the AE1 and pendrin, and the subcellular distribution of the H ϩ -ATPase (18,33). The subcellular localization of the H ϩ -ATPase within an intercalated cell subtype correlates with whether the cell secretes or absorbs net H ϩ equivalents (7,12).…”

Localization of a proton-pumping ATPase in rat kidney.

“…The complex H'ATPase labeling pattern seen in the distal nephron and the initial parts of the collecting duct system reveals heterogeneity of the non-intercalated cells in tubular epithelia that is also reflected by morphological differences (4). Labeling of these segments with antibodies against other antigens such as vitamin D-dependent calcium binding protein (50), Tamm-Horsfall glycoprotein (51), and carbonic anhydrase (38)(39)(40), also demonstrates the heterogeneous nature of these cells. Functional studies on the response of isolated, microdissected distal segments to hormones and various physiological stimuli is probably attributable to the presence of different cell types in the various regions examined (52).…”

“…The labeling was unusual in that it was present on both apical and basolateral plasma membranes, indicating a lack of polarized insertion of the H'ATPase in this cell type. The cells in this segment also have an appreciable level of basolateral Na', K+ ATPase activity (37), and an abundance of cytoplasmic carbonic anhydrase (38,39), suggesting a specialized function that awaits physiological studies for its elucidation. Weak to moderate apical H'ATPase staining was observed in the thick ascending limb of Henle, a segment that contains substantial carbonic anhydrase (39, 40).…”

Distal renal tubular acidosis in mice that lack the forkhead transcription factor Foxi1

“…Thus, Foxi1 expression appears to be a prerequisite for normal function of intercalated cells in the mature kidney. In an attempt to analyze the cellular composition of the distal nephron epithelium in Foxi1 -/-mice, we used Ab's against CAII (carbanhydrase II), a marker for intercalated cells (20,21), and AQP2 (aquaporin 2), a marker for principal cells (22,23). In WT epithelium we can identify subsets of cells positive for either marker, whereas in Foxi1 -/-kidneys the entire epithelium appears to consist of a single cell type positive for both markers.…”