Cell calcium levels of normal and cystic fibrosis nasal epithelium.
To determine whether epithelial ion transport abnormalities in cystic fibrosis (CF) might reflect abnormal regulation of intracellular Ca2+ levels, cytosolic free calcium (Cai2+) was measured using fura-2 or quin2 in suspensions of normal or CF nasal epithelial cells derived from primary cell culture. The basal Cai2+ level measured with fura-2 in CF nasal epithelia was 155 +/- 9 nM (n = 5), a value not significantly different from normal nasal epithelia (143 +/- 16 nM, n = 5). Total cell calcium was measured by atomic absorption spectroscopy and no differences were observed between CF (6.3 +/- 0.5 nmol/mg protein; n = 3) and normal (6.2 +/- 1.2 nmol/mg protein; n = 3) nasal epithelial cells. Placing Na+ loaded cells in a low (10 mM) extracellular Na+ solution resulted in a rapid increase in Cai2+ consistent with Ca2+ uptake via a plasmalemmal Na+-Ca2+ exchanger. The level of Cai2+ achieved by this low Na+ maneuver was not significantly different in CF cells compared to normal cells. Neither isoproterenol (10(-5) M) nor forskolin (10(-6) M) had any effect on Cai2+ in normal or CF nasal epithelial cells. Thus, it appears that differences in cell Cai2+, as measured by fluorescent chelators in suspensions of cultured cells, do not account for the abnormalities in basal or isoproterenol stimulated ion transport in CF tissues.
Murphy
E
E
National Institute of Environmental Health Sciences, Laboratory of Molecular Biophysics, Research Triangle Park, North Carolina 27709.
Cheng
E
E
Yankaskas
J
J
Stutts
M J
MJ
Boucher
R C
RC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000634:Aminoquinolines; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002648:Child; D000242:Cyclic AMP / Q000378:metabolism; D003550:Cystic Fibrosis / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D004987:Ethers / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D015759:Ionomycin; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D013054:Spectrophotometry, Atomic
D000634:Aminoquinolines; D001572:Benzofurans; D004987:Ethers; D005456:Fluorescent Dyes; D015759:Ionomycin; D010042:Ouabain; D012964:Sodium; D000242:Cyclic AMP; D007545:Isoproterenol; C035739:Quin2; D002118:Calcium; D016257:Fura-2