A voltage, calcium, and ATP sensitive non selective cation channel in human colonic tumor cells.
A non selective cation channel has been identified in the human colonic cell lines T84 and HT29D4 using the patch clamp technique. The channel is equally permeable to Na+ and K+, has a linear current-voltage relationship and a conductance of about 20 pS in symmetrical NaCl conditions. The channel is not permeable to chloride or to large organic cations such as N-methyl-D-glucamine. The open probability of the channel is voltage dependent. Cytosolic Ca2+ concentrations higher than 0.1 mM are required to activate the channel. The channel is blocked by cytosolic ATP (1 mM). 3',5-dichlorodiphenylamine-2-carboxylic acid and 5-nitro-2-(3-phenylpropylamino)-benzoic acid inhibit the channel when present on the extracellular side. The block is not voltage dependent. 3',5-dichlorodiphenylamine-2-carboxylic acid is the most potent blocker and completely inhibits channel activity at a concentration of 50 microM. The channel is insensitive to amiloride and derivatives.
Champigny
G
G
Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Valbonne, France.
Verrier
B
B
Lazdunski
M
M
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000230:Adenocarcinoma; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002999:Clone Cells; D005576:Colforsin / Q000494:pharmacology; D003110:Colonic Neoplasms; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects
D007473:Ion Channels; D005576:Colforsin; D000001:Calcimycin; D000255:Adenosine Triphosphate; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine