Antidiuretic hormone decreases the intracellular pH in distal nephron epithelium (A6) by inhibiting Na+/H+ exchange.
1. To clarify the effect of arginine vasotocin (AVT) on intracellular pH (pHi) of A6 cells (an amphibian renal cell line), we measured pHi with a single-cell fluorescent imaging system in an HCO3(-)-nominally-free medium. 2. AVT (40 mU/ml) significantly decreased pHi from 7.44 +/- 0.11 to 7.19 +/- 0.22 (mean +/- SE) by inhibiting the Na+/H+ exchanger. 3. A membrane-permeable analogue of cAMP, dibutyryl cAMP (1 mM), significantly decreased pHi from 7.40 +/- 0.02 to 7.17 +/- 0.02, a response similar to that of AVT. 4. These data indicate that, in A6 cells, AVT suppresses the Na+/H+ exchanger via a cAMP-dependent pathway and the Na+/H+ exchanger maintains pHi under HCO3(-)-nominally-free conditions.
Doi
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Division of Respiratory Research, Hospital for Sick Children Research Institute, University of Toronto Faculty of Medicine, Ontario, Canada.
Marunaka
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Y
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000663:Amphibians; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence; D009399:Nephrons / Q000187:drug effects / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors*; D014668:Vasotocin / Q000494:pharmacology*
D001639:Bicarbonates; D017923:Sodium-Hydrogen Exchangers; C039465:5-dimethylamiloride; D003994:Bucladesine; D000584:Amiloride; D000242:Cyclic AMP; D014668:Vasotocin