Cystic fibrosis transmembrane conductance regulator activates water conductance in Xenopus oocytes

1997 ◽  
Vol 434 (6) ◽  
pp. 841-847 ◽  
Author(s):  
R. Schreiber ◽  
R. Greger ◽  
R. Nitschke ◽  
K. Kunzelmann
Keyword(s):  
Cystic Fibrosis ◽  
Xenopus Oocytes ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Water Conductance ◽  
Cystic Fibrosis Transmembrane

Radiotracer studies of cystic fibrosis transmembrane conductance regulator expressed in Xenopus oocytes

1994 ◽  
Vol 266 (6) ◽  
pp. C1586-C1593 ◽  
Author(s):  
T. Ohrui ◽  
W. Skach ◽  
M. Thompson ◽  
J. Matsumoto-Pon ◽  
C. Calayag ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Carboxylic Acid ◽  
Phorbol Ester ◽  
Xenopus Oocytes ◽  
Disulfonic Acid ◽  
Transmembrane Conductance Regulator ◽  
Wild Type ◽  
Transmembrane Conductance ◽  
Urea Uptake ◽  
Cystic Fibrosis Transmembrane

We measured fluxes of radiotracers in Xenopus oocytes expressing the cystic fibrosis transmembrane conductance regulator (CFTR). Addition of adenosine 3',5'-cyclic monophosphate (cAMP)-elevating agents [forskolin and 3-isobutyl-1-methylxanthine (I/F)] led to large increases in uptake of 36Cl, 125I, and 82Br into oocytes expressing wild-type CFTR or delta F508 CFTR but not sham-injected oocytes. I/F also stimulated halide efflux from CFTR and delta F508 oocytes in the sequence Cl > Br > I. cAMP-induced increases in 36Cl efflux from delta F508 oocytes were approximately 20% of those in CFTR oocytes. Increases in halide efflux were blocked by diphenylamine-2-carboxylic acid but not by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. The phorbol ester, phorbol 12-myristate 13-acetate, also stimulated 36Cl efflux from CFTR oocytes. ATP uptakes into CFTR and sham oocytes were similar, and both were reduced by I/F. However, ATP uptake into I/F-treated CFTR oocytes was slightly greater (approximately 40%) than into I/F-treated sham oocytes. Urea uptake into CFTR and sham oocytes was similar and in both cases was increased by I/F. However, the I/F-induced increase in urea uptake into CFTR oocytes was significantly greater than for sham oocytes. I/F stimulated formate uptake into CFTR oocytes but not into sham oocytes. Fluxes of 22Na, 86Rb, 35SO4, 32PO4, and mannitol were unaltered by expression and activation of CFTR.

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