Na and K dependence of the Na/K pump in cystic fibrosis fibroblasts.

Reznik, Vivian; Schneider, Jerry A.; Mendoza, Stanley A.

doi:10.1073/pnas.78.11.7143

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

1981

DOI: 10.1073/pnas.78.11.7143

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Na and K dependence of the Na/K pump in cystic fibrosis fibroblasts.

Vivian Reznik¹,

Jerry A. Schneider²,

Stanley A. Mendoza³

Abstract: The Na and K dependence of the Na/K pump was measured in skin fibroblasts from patients with cystic fibrosis and age/sex-matched controls. Under basal conditions, there was no difference between control and cystic fibrosis cells in protein per cell, intracellular Na and K content, or Na/K pump activity (measured as ouabain-sensitive 86Rb uptake). There was no difference in the Na dependence of the Na/K pump between cystic fibrosis cells and control cells. In cells from patients with cystic fibrosis, the Na/K p… Show more

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1983

1989

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Cited by 5 publications

(3 citation statements)

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“…More recently, however, Reznik et al (12) reported a reduced affinity of the NaK pump for external K(Rb): K,,, was 2.2 mM for normal RBC and 4.6 in CF RBC. This finding paralleled their previous report that the affinity for external K of the NaK pump in cultured CF fibroblasts was reduced compared to normal cells (13), but both of these results are inconsistent with the finding of Boucher et al (7) that CF respiratory epithelium had increased Na pump activity (7).…”

supporting

confidence: 81%

“…Accordingly, physiologically important differences in the kinetic characteristics of the transport pathways studied might have been obscured. For this reason, and in view of the more recent reports of abnormaliteis in Na pump activity in CF red cells and other tissues (7,12,13), kinetic parameters of three major cation transport pathways in red cells were measured: the NaK pump, the NaK Co system, and the ouabain and bumetanide insensitive (residual) pathway. The results indicate that all of these pathways are kinetically normal in CF red cells.…”

mentioning

confidence: 99%

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Kinetic Parameters of Rubidium Transport Pathways Are Normal in Cystic Fibrosis Red Cells

Joiner

1988

Pediatr Res

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ABSTRACT. The abnormalities in ion transport in cystic fibrosis (CF) respiratory and sweat duct epithelia have prompted Studies of ion permeability in CF red blood cells (RBC) although previous reports have been contradictory. In this study, the kinetic characteristics of the three major cation transport systems in RBC were evaluated by measuring rubidium (Rb) uptake at various external Rb concentrations. The maximal velocity and affinity for external Rb (KH) of the NaK pump were normal in CF RBC, as were the maximal velocity and K, for Rb of the NaK cotransport system. Residual (ouabain and bumetanide insensitive) Rb uptake, and steady state RBC Na and K contents were also normal. These data indicate the NaK pump and cotransport system do not exhibit primary or secondary perturbations in CF RBC, and suggest that the noncarrier-mediated membrane permeability to cations is also normal in these cells. (Pediatr Res 24: 495-498, 1988) Abbreviations CF, cystic fibrosis RBC, red blood cell V , , maximal velocity K, Rb, external K or Rb PBS, phosphate-buffered saline OS, ouabain-sensitive Co, cotransport CF is an autosomal recessive disorder manifesting multiple exocrine abnormalities (1). The diagnostically important elevation of sweat chloride reflects malfunctioning of the salt resorbing mechanisms of sweat duct epithelium. Recent work has indicated that the basis of this dysfunction is low C1 permeability of the apical membrane of the ductal epithelial cells (2). Respiratory epithelia share this defect (3), which appears in these cells to arise from abnormalities of the adrenergic regulatory mechanisms of the C1 channel (4-6). Other recent studies of CF respiratory epithelia have also shown increased permeability of the apical membrane to Na, accompanied by elevated Na pump rates at the basolateral membrane, with increased numbers of [3H]ouabain binding sites and ouabain-inhibitable oxygen consumption (7). These findings suggest that, in addition to the C1 channel,

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confidence: 81%

mentioning

confidence: 99%

Kinetic Parameters of Rubidium Transport Pathways Are Normal in Cystic Fibrosis Red Cells

Joiner

1988

Pediatr Res

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“…We describe serial and cross-sectional body potassium measurements on 161 unselected CF patients between the ages of I month and 17 years to further quantify the nature of malnutrition in CF and its response to nutritional therapy. Two studies of intracellular potassium levels in CF have indicated normal intracellular concentrations of potassium in this disease (5,6).…”

mentioning

confidence: 99%

Total Body Potassium in Cystic Fibrosis

Shepherd,

Holt,

Greer

et al. 1989

J. pediatr. gastroenterol. nutr.

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To further evaluate the nature of malnutrition, define at‐risk groups, and confirm the efficacy of nutritional supplementation on body composition in cystic fibrosis (CF), we have conducted longitudinal and cross‐sectional studies of total body potassium (TBK) in 161 unselected CF subjects aged 1 month to 17 years. TBK was determined by measurement of 40K in a whole body counter, reflecting body cell mass (BCM), the vital work‐performing and growing cellular component of the body. Compared with normal TBK data for age and sex from pooled measurements of 1,629 healthy children aged 1 week to 17 years, CF infants (n = 12) diagnosed by newborn screening were depleted in TBK at diagnosis and showed catch‐up with therapy by 1 year; CF children aged 2–17 years (n = 140) showed a tendency for inadequate accretion of TBK (and thus BCM) with increasing age, although the normal correlation between TBK and weight and height was maintained in the majority suggesting a pattern of nutritional stunting of growth; and malnourished CF children (n = 9) showed significant catchup in TBK with long‐term nutritional rehabilitation (85–98% of TBK predicted for weight and height). These studies suggest that potentially serious, but possibly correctable deficits, in the growth of the body cell mass as measured by TBK occur commonly in CF. These deficits may be established very early in life and if not corrected lead to progressive nutritional growth retardation with increasing age.

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Thermal sweat lactate in cystic fibrosis and in normal children

Fellmann¹,

Labbé²,

Gachon³

et al. 1985

Europ. J. Appl. Physiol.

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We attempt to determine whether the decrease in Na+ reabsorption and the increase in K+ secretion in sweat of cystic fibrosis patients (CF) were associated with changes in glandular anaerobic metabolism evaluated by forehead sweat lactate excretion rate. 6 CF and 11 normal (C) children, 5 months to 14 years old, were exposed to external thermal load (45 degrees C). The data showed that: 1) Na+, K+ and Cl- concentrations in CF are constant at any flow rate (Qsw); 2) In both groups the excretion rates of Na+, K+ and Cl- increased linearly with Qsw but the slopes in CF were significantly higher than in C (p less than 0.001); 3) Lactate excretion rate increased with Qsw as in CF and C with the same slope. We suggest that an increase in energy expenditure of Na+ - K+ exchange and an active secretion of K+ by the duct could explain the normal energy metabolism that we observed in CF sweat glands.

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Na and K dependence of the Na/K pump in cystic fibrosis fibroblasts.

Cited by 5 publications

References 20 publications

Kinetic Parameters of Rubidium Transport Pathways Are Normal in Cystic Fibrosis Red Cells

Kinetic Parameters of Rubidium Transport Pathways Are Normal in Cystic Fibrosis Red Cells

Total Body Potassium in Cystic Fibrosis

Thermal sweat lactate in cystic fibrosis and in normal children

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