Stimulation of Cl- secretion by AlF4- and vanadate in T84 cells.
We investigated the mechanism of Cl- secretion by fluoroaluminate(AlF4-) and sodium orthovanadate(vanadate) using the human colonic T84 cell line. T84 cell monolayers grown on collagen-coated filters were mounted in Ussing chambers to measure short circuit current(ISC). Serosal addition of AlF4- or vanadate to T84 monolayers produced a sustained increase in ISC. Removal of Ca2+ from the serosal bathing solution partially inhibited AlF4-(-)and vanadate-induced ISC, and readministration of Ca2+ restored AlF4-(-)and vanadate-induced ISC. Carbachol application in the presence of forskolin, AlF4- or vanadate induced a synergistic increase of ISC. Forskolin and vanadate significantly increased cellular cAMP level, while carbachol and AlF4- did not. Carbachol, AlF4- and vanadate significantly increased [Ca2+]i. After Na+ in mucosal bathing solution was replaced with K+, and the mucosal membrane of T84 cell was permeabilized with amphotericin B, AlF4-, vanadate, and carbachol increased K+ conductance, but forskolin did not. After sodium chloride in serosal bathing solution was replaced with sodium gluconate and the serosal membrane was permeabilized with nystatin, forskolin, AlF4-, and vanadate increased Cl- conductance, but carbachol did not. AlF4-(-)induced ISC was remarkably inhibited by the pretreatment of pertussis toxin(2 micrograms/ml) for 2 hours. These results indicate that AlF4- and vanadate can increase Cl- secretion via simultaneous stimulation of Cl- channel and K+ channel in T84 cells. However, the AlF4- action is mostly attributed to stimulation of pertussis toxin-sensitive G-proteins, whereas the vanadate action mostly results from G protein-independent mechanisms.
Hwang
T H
TH
Department of Oral Biotechnology, College of Dentistry, Pusan National University, Korea.
Jung
J S
JS
Bae
H R
HR
Yun
I
I
Lee
S H
SH
D000535:Aluminum / Q000494:pharmacology*; D000666:Amphotericin B / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D016764:Cell Polarity; D002478:Cells, Cultured / Q000187:drug effects; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology*; D002712:Chlorides / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D003106:Colon; D004594:Electrophysiology; D005461:Fluorine / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D037342:Pertussis Toxin; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D015290:Second Messenger Systems; D015398:Signal Transduction; D014638:Vanadates / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D015221:Potassium Channels; D010566:Virulence Factors, Bordetella; D005576:Colforsin; C053629:fluoroaluminum; D005461:Fluorine; D014638:Vanadates; D000666:Amphotericin B; D002217:Carbachol; D000535:Aluminum; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D011188:Potassium