NaK stimulated adenosinetriphosphatase: Intracellular localisation within the proximal tubule of the rat nephron

Schmidt, Udo; Uc, Dubach

doi:10.1007/bf00588617

Cited by 69 publications

(24 citation statements)

References 10 publications

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“…In fact, the inhibition of the transport enzyme Na-K-ATPase (30) suggests the occurrence of a defective ATP synthesis. In our study, major membranous changes were seen at the base of the cell where the Na-K-ATPase involved in active transport is localized (31)(32)(33)(34). While the brush border structure of the proximal nephron appeared to be well preserved (28,29) (35), who showed that maleic anhydride reacts rapidly and specifically with amino groups associated with the protein fraction of the red cell membrane.…”

Section: Introductionmentioning

confidence: 50%

Membrane permeability as a cause of transport defects in experimental Fanconi syndrome. A new hypothesis.

Bergeron¹,

Dubord²,

Hausser³

et al. 1976

J. Clin. Invest.

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A B S T R A C T The injection of sodium maleate (200-400 mg/kg) into rats produces aminoaciduria along with glycosuria and phosphaturia, resembling the Fanconi syndrome. This experimental model was studied by means of microinjections into proximal convoluted tubules of the kidney, stop-flow diuresis, and microperfusion of single nephrons. Our results show that, in maleate-treated rats, competition between amino acids of related structures (L-proline, L-OH-proline, and glycine) possesses the same characteristics, and net influx of amino acids appear normal at the proximal nephron. Data obtained by classical stop-flow techniques and single nephron microperfusions also indicate a normal entry of labeled amino acids (L-lysine, glycine, L-valine, L-proline, L-cystine), and 3-0-methyl-D-[3H]glucose and ['P]phosphate from the luminal side of the proximal tubule cell. However, the efflux of molecules from the cell appears enhanced throughout the proximal and distal tubule; molecules that exit at this site are excreted directly into the urine. Our results suggest that the phosphaturia, aminoaciduria, and glycosuria of the experimental Fanconi syndrome can be explained by a modification of the cell membrane permeability (increased efflux) at distal sites of the nephron rather than by a modification of the membrane transport (decreased influx) at the proximal sites, as is currently accepted. Our data also stress the importance of efflux phenomena in membrane transport.

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Section: Introductionmentioning

confidence: 50%

Membrane permeability as a cause of transport defects in experimental Fanconi syndrome. A new hypothesis.

Bergeron¹,

Dubord²,

Hausser³

et al. 1976

J. Clin. Invest.

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“…Because of the functional and cellular nephron segment heterogeneity (12,181, determinations of Na-K-ATPase activity on broken cell homogenates of cortex, medulla, or papilla, which contain a mixture of diverse nephrons as well as tubular and nontubular cells, were subject to limitations. The knowledge of the physiological role of the enzyme in electrolyte handling and adaptation has therefore considerably progressed as methods allowing measurement of the enzyme activity in discrete nephron segments have become available (6, 21,22) and have made possible the correlation of Na-K-ATPase activity with tubular ion transport and the detection of physiological alterations in definite parts of the nephron. Practically, this has been mainly realized by methods relying on enzyme microanalysis or ouabain binding studies on microdissected tubules (7).…”

mentioning

confidence: 99%

Quantification of renal Na‐K‐ATPase activity by image analysing system

Laborde¹,

Bussières²,

Smet³

et al. 1990

Cytometry

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The localisation of renal Na‐K‐ATPase activity along the rat nephron by a cytochemical method, and its quantification by an image analysis system, are described in this paper. Frozen kidney sections were exposed to a trapping agent, the lead ammoniac‐citrate‐acetate complex (LACA), and to all the substrates necessary to the enzyme acitvity. The absorbance of the histochemical reaction product (precipitated in situ), proportional to the enzymatic activity, was then measured through the analysis of the grey levels of the transmitted image of the kidney section. This method was both sufficiently sensitive and technically simple to permit measurements of the enzyme in large numbers of tubules and to determine its activity in each region of the nephron. The Na‐K‐ATPase activity has been determined in the proximal convoluted tubule (PCT), the medullary thick ascending limb of the Henle's loop (mTAL), and the distal convoluted tubules (DCT) of the rat nephron. The Na‐K‐ATPase distribution shows an activity per millimeter tubule length higher in the DCT than in the mTAL and the PCT: 1,406 ± 33, 823 ± 64, and 350 ± 71 pmoles Pi/tubule mm/h, respectively. In conclusion, the described method allows the segmental quantification of Na‐K‐ATPase activity at a cellular level and offers a precise approach to the analysis of this enzyme along the length of nephrons.

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“…One sample of the distal convolution was required for each ATPase. The ATPase was measured with the oil-well technique utilizing an enzymatic cycling reaction (14). All operations for loading and pipetting were performed under a stereomicroscope.…”

Section: Methodsmentioning

confidence: 99%