Figure 6.

Effect of CO₂ exposure on expression of V-ATPase and apical membrane area of proton-secreting cells in the turtle urinary bladder. Image shows a whole mount view of the apical epithelial surface of a turtle urinary bladder stained with antibodies against the “A” subunit of the V-ATPase, followed by secondary donkey anti-rabbit Ig coupled to Alexafluor 488. The V-ATPase-rich cells (arrows) show a remarkable increase in surface area between the control (A) and tissues acutely exposed to basolateral CO₂ (B), indicating that CO₂ rapidly activates these cells. Tissue was kindly provided by Dr. John Schwartz, Boston University Medical Center, Boston who exposed bladders to CO₂ as part of the annual “Origins of Renal Physiology” course at Mount Desert Island Biological Laboratories, Bar Harbor, ME. Bar = 10 µm.