ISSN:
1432-2013
Keywords:
Key words Brush-border
;
Membrane vesicle
;
Cystic fibrosis transmembrane regulator (cftr)
;
Alternate Cl
;
conductance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstracts Brush-border membrane vesicles (BBMV) were prepared from whole Balb/c mice kidneys by a Mg2+ precipitation technique. The presence of an intrinsic Cl–conductance co-expressed with Na+/glucose cotransport was inferred by the anion dependence of [14C]glucose uptake and overshoot with inward Na+-anion gradients. In Na+-equilibrated conditions, an inside-negative membrane potential difference (p.d.) produced by an inward Cl–gradient alone was capable of driving intravesicular [14C]glucose accumulation. The apparent anion conductance had a selectivity of Br– = I– = Cl– 〉 F–〉〉 gluconate, was inhibited by 0.5 mM 5-nitro-2- (3-phenylpropylamino)-benzoic acid (NPPB) but was unaffected by 0.5 mM 4,4′-diisothiocyanatostilbene 2,2′-disulphonate (DIDS). BBMV were isolated from mice in which the CFTR gene had been disrupted by a termination mutation (–/–) and compared with normal litter mates (+/+) and heterozygotes (–/+)[18]. [14C]Glucose uptake in NaCl media was significantly greater than glucose uptake in Na gluconate media for all three genotypes measured at 20 s: for homozygous –/– animals [14C]glucose uptake was increased by 2.80 ± 0.53 fold in Cl–media compared to gluconate media, n = 6; for wild-type +/+, by 2.16 ± 0.53 fold, n = 8; and for heterozygous +/– animals, by 2.17 ± 0.45 fold, n = 8. The observation of a Cl–-dependent component in BBMV isolated from homozygous –/– mutant animals shows that the chloride conductance in these vesicles cannot be due to cftr expression.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004240050438
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