Sodium Bicarbonate Category

A second role for the NBC protein might be an involvement in intracellular pH homeostasis in principal cells. As mentioned above, our recent studies have shown that luminal proton secretion in the vas deferens involves a chloride-independent, SITS-sensitive bicarbonate transporter, indicating the possible role of an Na+-HCO3~ cotransporter. Further studies will be required to reveal […]

Also of interest is the abundance of the NBC protein both in principal cells and in apical/narrow cells that extrude protons via an apical H+ATPase. It is possible that the Na+-HCO3~ cotransporter has a different role in these two distinct cell types. The apical/narrow cells are greatly enriched in the cytoplasmic isoform of carbonic anhydrase, […]

Basolateral HCO3 extrusion in epithelial cells can be mediated by a Cl_/HCO3_ anion exchanger such as AE1, as seen in specialized proton-secreting intercalated cells in the kidney; or alternatively it can be achieved by the activity of a basolateral Na+-HCO3~ cotransporter, similar to that present in renal proximal tubules. Our present results show that an […]

Acidification of the male reproductive tract has an important role in sperm maturation and storage, but the transport pathways involved in this key function of the epithelium lining the excurrent ducts are poorly understood in vivo. Previous studies have implicated an Na+-dependent process, probably an Na+/H+-exchanger, in luminal acidification, while recent work from our laboratory […]

Electron Microscopy By conventional light and electron microscopy, apical/ narrow cells have several morphological characteristics distinct from those of principal cells, including a dark cytoplasm, many mitochondria, numerous vesicles beneath the apical plasma membrane, and an oval nucleus located in the mid to apical part of their cytoplasm. Figure 4A shows a transverse section through […]

Immunofluorescence Indirect immunofluorescence staining of the epididymis for NBC was dependent upon pretreatment of the tissue sections with SDS, an antigen-retrieval technique, prior to application of the primary antibody. The anti-NBC antibody produced a strong basolateral staining in epithelial cells in the initial segment (Fig. 3A) and in tubules of the intermediate zone (see for […]

Western Blotting As shown in Figure 1 (lane 2), Western blotting of the epididymis with the anti-NBC antibody revealed a single band at about 160 kDa. This band was almost completely abolished when the antibody was preabsorbed with the immunizing peptide (Fig. 1, lane 4), and neither preimmune serum nor secondary antibody alone revealed any […]