| 9108631 |
Iwase N, Sasaki T, Shimura S, Yamamoto M, Suzuki S, Shirato K: ATP-induced Cl- secretion with suppressed Na+ absorption in rabbit tracheal epithelium. Respir Physiol. 1997 Feb;107(2):173-80.
The effect of extracellular ATP on ion transport of rabbit tracheal epithelium was examined using an Ussing chamber. Isoproterenol (10 (-8)-10 (-5) M) did not alter the electrophysiological properties across the tracheal epithelium. Apically applied ATP induced an initial transient increase in short circuit current (SCC) followed by a decline to below the prior baseline. The initial increase by ATP (10 (-4) M) was significantly inhibited by a Cl (-) -channel inhibitor diphenylamine-2-carboxylate (DPC, 5 x 10 (-4) M) and Cl (-) -substitution with gluconate in the bath solution, while a cystic fibrosis transmembrane regulator (CFTR) Cl (-) -channel inhibitor glibenclamide (10 (-4) M), a Na (+)-channel inhibitor amiloride (10 (-4) M) and a K (+) -channel inhibitor quinidine (10 (-4) M) all failed to alter it. The decline in SCC by ATP was abolished by amiloride, while DPC or Cl-substitution with gluconate in the bath solution did not alter it. Ca (2+)-removal from the bath solutions did not significantly alter the initial increase nor the decline by ATP. Ionomycin (10 (-5) M) induced an initial transient increase in SCC, to a degree similar to that by ATP alone. A calmodulin antagonist W-7 reduced the SCC baseline and abolished SCC increase by ATP. These findings indicate that ATP activates Ca (2+)-dependent Cl (-) -channels with an inhibition of Na -channel activity or absorption in rabbit tracheal epithelium. |
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