Emerging Role of the Calcium-Activated, Small Conductance, SK3 K+ Channel in Distal Tubule Function: Regulation by TRPV4
Figure 5
Immunohistochemical staining of SK3 in the collecting duct.
Section (5 µm) from WT mouse kidney showing staining for AQP2 (red), a marker of PCs in collecting duct, and SK3 (green). Panels A, C, and E are low magnification views of a cross-section through a CCD identified by AQP2 staining. Panels B, D, and F represent a magnified view of the inset area from A (yellow inset box). Panel B shows strong AQP2 staining along the luminal border of PCs (5–6 cells), but not of the ICs (2 cells without staining). As shown in D and F, strong staining of SK3 is evident along the luminal border of all cells, both PCs and ICs. Variable, but weak staining, is also apparent along the abluminal border of some cells. However, the staining is most pronounced along the luminal border for both PCs and ICs, although typically stronger in PCs, as indicated by the SK3 fluorescence line intensity profiles across (luminal to abluminal direction) two cells identified as PC and IC (Panel G). H. Relative mean intensity profiles (± SEM) across the cells from all sections showing the maximal values across the luminal border (Apical) and abluminal border (Basal) and the minimal values within the cytoplasm (Cytosol). The mean values are given for both PCs (n = 37) and ICs (n = 12) from all sections analyzed. The maximal luminal intensity is much greater than the abluminal intensity (*P<0.02) indicating dominant expression at the luminal border. Scale bar is 10 µm.