Changes in pH affect Cl- removal and AVP action in collecting tubules.
We examined what mechanisms are involved in the alteration by chloride (Cl-) removal of arginine vasopressin (AVP)-induced cellular cAMP production, and cellular free calcium ([Ca2+]i) mobilization in rat renal papillary collecting tubule cells in culture, using two buffer systems: bicarbonate and non-bicarbonate buffers. The first study was performed in the bicarbonate-supplemented buffer. Removal of Cl-, which was replaced by methylsulfonate or gluconate, increased cellular pH (pHi) from 7.19 to 7.26. AVP increased cellular cAMP production in a dose-dependent manner; 1 x 10(-9) and 1 x 10(-7) M AVP-induced increases in cellular cAMP production were significantly enhanced by the Cl- removal. Also, 1 x 10(-7) M AVP-mobilized [Ca2+]i was augmented by the Cl- removal (181.3 vs. 224.5 nM, P < 0.05). The second study was carried out with the Krebs-Ringer buffered saline (KRB). Removal of Cl- lowered pHi from 7.20 to 7.09. AVP-induced increases in cellular cAMP production were significantly reduced in the Cl(-)-free KRB compared to those in the KRB. The reduction was obtained with KRB containing less than 25 mM Cl-. Similar results were obtained with 2 x 10(-8) M forskolin, a diterpene activator of adenylate cyclase. 1 x 10(-7) M AVP-mobilized [Ca2+]i was also diminished by the Cl(-)-free KRB. These results indicate that Cl- depletion affects the cellular response to AVP mediated via the changes in pHi in renal papillary collecting tubule cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Ishikawa
S
S
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Okada
K
K
Saito
T
T
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001639:Bicarbonates / Q000494:pharmacology; D002021:Buffers; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley
D001639:Bicarbonates; D002021:Buffers; D002712:Chlorides; D001127:Arginine Vasopressin; D005576:Colforsin; D000242:Cyclic AMP; D002118:Calcium