Fig. 3.

Effect of metabolic acidosis on renal Rhbg immunolabel. Immunolocalization of Rhbg confirmed increases in Rhbg expression after 5 days of HCl acid loading. In all panels, signal for Rhbg immunoreactivity is brown; H⁺-ATPase immunoreactivity is blue. A and B: 5 days HCl acid loading (B) increased Rhbg immunoreactivity in the connecting segment (CNT) and initial collecting tubule compared with control (A). C and D: no differences in cortical collecting duct (CCD) Rhbg immunoreactivity were apparent in control vs. 5-day HCl diet mice. Intercalated cells (arrows) are identified by intense basolateral Rhbg immunolabel and prominent apical H⁺-ATPase, and principal cells (arrowheads) by moderate basolateral Rhbg immunolabel and minimal or no apical H⁺-ATPase. E and F: in the outer medullary collecting duct in the outer stripe (OMCDo), Rhbg immunoreactivity in both intercalated cells (arrows) and principal cells (arrowheads) was increased by 5-day HCl loading. G and H: increased intercalated and principal cell Rhbg immunolabel and intercalated cell hypertrophy in the OMCD in the inner stripe (OMCDi) in response to HCl metabolic acidosis.