Localization and vasopressin regulation of the Na+-K+-2Cl- cotransporter in the distal colonic epithelium

Figure 2 Effect of vasopressin on the cellular and subcellular location of Na⁺-K⁺-2Cl^-1 cotransporter and Na⁺-K⁺-2Cl^- cotransporter 2. Vasopressin-induced redistribution of Na⁺-K⁺-2Cl^- cotransporter (NKCC2) in the mouse distal colon (A-C). Mice were treated with saline (A) or dDAVP (10 ng) (B: 15 min; C: 30 min; D: 1h), and NKCC2 and NKCC1 immunolabeling was performed. A-D: Lower magnification images. Higher magnification images of the white rectangles in the corresponding A-D images. The arrow and asterisk indicate increased apical NKCC2; arrowheads indicate NKCC2 localization. Most of the NKCC2 labeling appears to be intracellular in the control mice. NKCC2 recruitment to the apical membranes of enterocytes at 30 min and 1 h post-stimulation is shown (C and D arrow and asterisk). However, vasopressin seemed to have no obvious effects on the redistribution of NKCC1 (I, J). Apical membrane NKCC2 and basolateral NKCC1 fluorescence intensity in saline- or dDAVP-treated distal surface epithelia was normalized to the apical or basolateral membrane in the saline-treated mouse. A significant difference in NKCC2 and NKCC1 intensity was observed at 15 min, 30 min and 1 h compared with that in the unstimulated state (E-H). N = 3 mouse, n = 6 images, n’ = 4-12 selected area; ^bP < 0.01; ^dP < 0.01.