Microtubule-dependent relocation of branchial V-H+-ATPase to the basolateral membrane in the Pacific spiny dogfish (Squalus acanthias): a role in base secretion

• Published in: Journal of Experimental Biology
• Main Authors: Tresguerres, Martin, Parks, Scott K., Katoh, Fumi, Goss, Greg G.
• Format: Text
• Language: English
• Published: Company of Biologists 2006
• Subjects: Research Article; Pacific; spiny dogfish; Squalus acanthias
• Online Access: http://jeb.biologists.org/cgi/content/short/209/4/599; https://doi.org/10.1242/jeb.02059

We have previously shown that continuous intravenous infusion of NaHCO 3 for 24 h (∼1000 μmol kg-1 h-1) results in the relocation of V-H+-ATPase from the cytoplasm to the basolateral membrane in the gills of the Pacific dogfish. To further investigate this putative base-secretive process we performed similar experiments with the addition of colchicine, an inhibitor of cytoskeleton-dependent cellular trafficking processes. Blood pH and plasma total CO 2 were significantly higher in the colchicines-treated, HCO 3 --infused fish compared with fish infused with HCO 3 - alone. The effect of colchicine was highest after 24 h of infusion (8.33±0.06 vs 8.02±0.03 pH units, 15.72±3.29 vs 6.74±1.34 mmol CO 2 l-1, N =5). Immunohistochemistry and western blotting confirmed that colchicine blocked the transit of V-H+-ATPase to the basolateral membrane. Furthermore, western blotting analyses from whole gill and cell membrane samples suggest that the short-term (6 h) response to alkaline stress consists of relocation of V-H+-ATPases already present in the cell to the basolateral membrane, while in the longer term (24 h) there is both relocation of preexistent enzyme and upregulation in the synthesis of new units. Our results strongly suggest that cellular relocation of V-H+-ATPase is necessary for enhanced HCO 3 - secretion across the gills of the Pacific dogfish.