Chloride uptake into cultured airway epithelial cells from cystic fibrosis patients and normal individuals.

Stutts, M. Jackson; Cotton, Calvin U.; Yankaskas, James R.; Cheng, Elaine; Knowles, Michael R.; Gatzy, J. T.; Boucher, Richard C.

doi:10.1073/pnas.82.19.6677

Cited by 48 publications

(22 citation statements)

References 13 publications

(19 reference statements)

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“…The three to four times larger amiloride-sensitive oxygen consumption in CF tissues is consistent with the notion that a greater quantity of substrate for the Na+ pump enters CF cells through an amiloride-sensitive path. Thus, the greater effect of amiloride in CF tissues is compatible with both a decreased chloride conductance (22)(23)(24) and an increased sodium conductance in the apical cell membrane (22).…”

Section: Discussionmentioning

confidence: 82%

“…CF nasal polyp epithelium has been previously characterized as less permeable to chloride ion (3,13). This defect was shown to be located in the apical cell membrane (22) and to be retained in cell culture (23). More recent studies reveal abnormal sodium transport, including a greater net (active) sodium absorption by CF airway epithelium (27) that correlates with a greater sodium ionic conductance of the apical cell membrane (22).…”

Section: Discussionmentioning

confidence: 99%

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Oxygen Consumption and Ouabain Binding Sites in Cystic Fibrosis Nasal Epithelium

et al. 1986

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ABSTRACT. Ion transport by the epithelium lining the airways of patients with cystic fibrosis (CF) is characterized by a raised transepithelial PD and an increased amiloride sensitivity (I). These properties could arise from normal sodium transport across an epithelium with decreased cell chloride permeability and limited chloride secretion. Alternatively, a higher than normal rate of sodium absorption could contribute to these abnormalities. We investigated the latter possibility by measuring oxygen consumption and specific ouabain binding of CF and atopic polyp epithelia and normal turbinate epithelium. Tissue from CF patients consumed oxygen at a rate that was two to three times that of non-CF tissues and had 60% more ouabain binding sites than non-CF epithelium. These results are not consistent with an isolated defect in chloride permeability but support recent findings that the sodium conductance of the apical cell membrane and net sodium absorption by CF nasal epithelium are greater than those of non-CF nasal epithelium. In CF, ion transport by airway epithelium is markedly abnormal (1, 2). The lumen negative PD generated in vivo by the nasal or tracheobronchial epithelium of CF patients is 2-to 3-fold greater than that of normal or disease control individuals (1) and hyperpolarizes less in response to superfusion with a chloridefree solution (3). Parallel findings in studies of sweat gland ductal epithelium have been interpreted as evidence for reduced membrane chloride permeability that traps salt in the duct lumen (4, 5). The more complete inhibition of airway PD by superfused amiloride, in vivo, is also consistent with the absence of a functioning chloride secretory path in CF airways (1, 2). Others have speculated, based on this reasoning, that the functional defect in CF airway epithelia is deficient chloride conductance (4). Alternatively, the greater amiloride eficacy and raised PD in CF airway epithelia could reflect both a decreased chloride permeability and an increased sodium absorptive rate.In epithelia that are dependent on operation of the Na+-K+-ATPase for ion transport, variations in transport rate can be paralleled by changes in indices of Na+-K+-ATPase activity. For example, increased ATP hydrolysis and numbers of sodium pumps have been found to accompany increases in sodium absorption by renal tubules (6) and chloride secretory capacity was paralleled by pump activity in shark rectal gland (7). In dog trachea, a predominantly chloride secreting airway epithelium, inhibition of chloride secretion caused a decrease in ouabainsensitive oxygen consumption (8). We reasoned that if the defect in cell chloride permeability in CF airways caused decreased chloride secretion, then hydrolysis of ATP by the Na+-K+-ATPase in CF cells would be normal or even reduced. On the other hand, if sodium absorption is increased in CF airway epithelium, then the synthesis and hydrolysis of ATP devoted to sodium pump activity should be greater than normal because of faster pump turnover and/or increased pump de...

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Oxygen Consumption and Ouabain Binding Sites in Cystic Fibrosis Nasal Epithelium

et al. 1986

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“…. These fluorescent indicators, introduced by Tsien and coworkers (1 [8][9][10][11][12][13][14][15][16][17][18][19][20], are loaded into cells as the acetoxymethyl ester of quin2 or fura-2. Once inside the cell intracellular esterases cleave the acetoxymethyl ester to produce the free acid of the calcium chelator and by-products acetate and formaldehyde.…”

Section: Discussionmentioning

confidence: 99%

“…Basal Cai2+ levels were measured and the presence of a Na+-Ca3+ exchange process, and responses to selected pharmacologic agonists were tested. Cultured nasal cells were chosen for study because of their availability and because the C1-permeability defect that characterizes CF has been reported to be retained in this preparation (16).…”

mentioning

confidence: 99%

Cell Calcium Levels of Normal and Cystic Fibrosis Nasal Epithelium

et al. 1988

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ABSTRACT. To determine whether epithelial ion transport abnormalities in cystic fibrosis (CF) might reflect abnormal regulation of intracellular Caz+ levels, cytosolic free calcium (Caiz+) was measured using fura-2 or quin2 in suspensions of normal or CF nasal epithelial cells derived from primary cell culture. The basal Ca?+ level measured with fura-2 in CF nasal epithelia was 155 f 9 nM (n = 5), a value not significantly different from normal nasal epithelia (143 f 16 nM, n = 5). Total cell calcium was measured by atomic absorption spectroscopy and no differences were observed between CF (6.3 f 0.5 nmollmg protein; n = 3) and normal (6.2 f 1.2 nmollmg protein; n = 3) nasal epithelial cells. Placing Na+ loaded cells in a low (10 mM) extracellular Na+ solution resulted in a rapid increase in Ca2+ consistent with CaZ+ uptake via a plasmalemmal Na+-Caz+ exchanger. The level of Cai2' achieved by this low Na+ maneuver was not significantly different in CF cells compared to normal cells. Neither isoproterenol (lom5 M) nor forskolin M) had any effect on Ca?+ in normal or CF nasal epithelial cells. Thus, it appears that differences in cell Caiz+, 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. (Pediatr Res 24: 79-84,1988) Abbreviations Cai2+, cytolsolic free calcium CF, cystic fibrosis AM, acetoxymethyl ester TCA, trichloroacetic acid PMN, polymorphonuclear cellsThe pathophysiology of CF appears to reflect abnormal epithelial ion transport functions in specific target epithelia (1, 2). Recent evidence has focused on the notion that the abnormalities in epithelial ion transport in the lung reflect dysfunctions in regulatory processes rather than abnormalities in the permeability properties of channel proteins. Evidence for this notion has accrued from two lines of investigation. First, studies of freshly excised nasal epithelia have shown that there is 1) an imbalance between the basal rate of Na+ absorption and the capacity to secrete C1-in CF as compared to normal tissues (3); and 2) the response to P-adrenergic agonists qualitatively differs in the two preparations, i.e., isoproterenol induces C1-secretion in normal

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“…To our knowledge, decreased Cl-concentration in cultured CF cells has not been reported before, although data presented by Stutts et al (18) did show a 10% lower level of Cl-in cells cultured from CF nasal epithelium. This difference was not statistically significant (18), but our findings suggest that intracellular Cl-should be examined more closely in affected epithelial cells.…”

Section: Discussionmentioning

confidence: 48%

Altered chloride metabolism in cultured cystic fibrosis skin fibroblasts.

Mattes¹,

Maloney²,

Littlefield³

1987

Proc. Natl. Acad. Sci. U.S.A.

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An abnormal regulation of chloride permeability has been described for epithelial cells from patients with cystic fibrosis (CF). To learn more about the biochemical basis of this inherited disease, we have studied chloride metabolism in cultured CF fibroblasts by comparing the efflux of 36C6-from matched pairs of CF and normal fibroblasts. The rate constants describing 36C6-efflux did not differ between the two cell types, but in each of the four pairs tested the amount of 36C6-contained within CF cells was consistently reduced, by 25-30%, relative to normal cells. Comparisons of cell water content and 22Na' efflux showed no differences between the two

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Chloride uptake into cultured airway epithelial cells from cystic fibrosis patients and normal individuals.

Cited by 48 publications

References 13 publications

Oxygen Consumption and Ouabain Binding Sites in Cystic Fibrosis Nasal Epithelium

Oxygen Consumption and Ouabain Binding Sites in Cystic Fibrosis Nasal Epithelium

Cell Calcium Levels of Normal and Cystic Fibrosis Nasal Epithelium

Altered chloride metabolism in cultured cystic fibrosis skin fibroblasts.

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