Exocytosis regulates urinary acidification in turtle bladder by rapid insertion of H+ pumps into the luminal membrane.
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<jats:p>Urinary acidification by the turtle bladder is due to a H+-ATPase that is located in the luminal membrane. The rate of H+ transport is stimulated by an increase in the ambient CO2. Using the fluorescent dye acridine orange, we showed that the mitochondria-rich cell of this equilibrium contains vesicles whose internal pH is acidic. We measured the pH of these vesicles by using endocytosed fluorescein isothiocyanate-labeled dextran and found it to be near 5.0. The pH increased after treatment with protonophores or metabolic inhibitors, suggesting that it was due to a H+ pump rather than to a Donnan effect. In bladders preloaded with fluorescent dextran, CO2 stimulated exocytosis and H+ transport measured simultaneously in the same bladder. The increase in the H+ current correlated well with the extent of exocytosis, and both were inhibited by pretreatment with colchicine. We conclude that the turtle bladder contains an intracellular reserve of vesicles containing H+ pumps and CO2 stimulates rapid fusion of these vesicles with the luminal membrane with consequent insertion of H+ pumps, thereby stimulating H+ secretion across the whole epithelium.</jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 79 (14), 4327-4331, 1982-07
Proceedings of the National Academy of Sciences
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詳細情報 詳細情報について
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- CRID
- 1360574096429026176
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- NII論文ID
- 30016263401
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- ISSN
- 10916490
- 00278424
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- データソース種別
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