The stepwise hydrolysis of adenine nucleotides by ectoenzymes of rat renal brush-border membranes

Čulić, Ognjen; Sabolić, Ivan; Žanić‐Grubišić, Tihana

doi:10.1016/0005-2736(90)90249-n

Cited by 37 publications

(21 citation statements)

References 40 publications

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“…That OK cells, which express many features of proximal tubular cells (27)(28)(29), were able to convert extracellular cAMP into AMP and adenosine on the one hand, and could synthesize ATP and, ultimately, cAMP from uptaken adenosine on the other hand (Fig. 4) is in line with previous reports on renal brush border membranes and proximal tubules: rat renal brush-border membranes were reported to express the activity of ecto-enzymes, including phosphodiesterases (30) and 5 '-nucleotidase (3 1 ) responsible for stepwise hydrolysis of adenine nucleotides (32). Several lines of evidence support the view that intracellularly accumulated [3 …”

Section: Discussionsupporting

confidence: 91%

Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication.

Friedlander

Couette²,

Coureau³

1992

J. Clin. Invest.

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The mechanism of phosphaturia induced by cAMP infusion and the physiological role ofextracellular cAMP in modulation of renal phosphate transport were examined. In cultured opossum kidney cells, extracellular cAMP (10-1,000 AM) inhibited Na-dependent phosphate uptake in a time-and concentration-dependent manner. The effect ofcAMP was reproduced by ATP, AMP, and adenosine, and was blunted by phosphodiesterase inhibitors or by dipyridamole which inhibits adenosine uptake. I3HIcAMP was degraded extracellularly into AMP and adenosine, and radioactivity accumulated in the cells as labeled adenosine and, subsequently, as adenine nucleotides including cAMP. Radioactivity accumulation was decreased by dipyridamole and by inhibitors of phosphodiesterases and ecto-5'-nucleotidase, assessing the existence of stepwise hydrolysis of extracellular cAMP and intracellular processing of taken up adenosine. In vivo, dipyridamole abolished the phosphaturia induced by exogenous cAMP infusion in acutely parathyroidectomized (APTX) rats, decreased phosphate excretion in intact rats, and blunted phosphaturia induced by PTH infusion in APTX rats. These results indicate that luminal degradation of cAMP into adenosine, followed by cellular uptake of the nucleoside by tubular cells, is a key event which accounts for the phosphaturic effect of exogenous cAMP and for the part of the phosphaturic effect of PITH which is mediated by cAMP added to the tubular lumen under the influence of the hormone. (J.

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Section: Discussionsupporting

confidence: 91%

Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication.

Friedlander

Couette²,

Coureau³

1992

J. Clin. Invest.

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“…However, this is not the site involved here, since under the conditions used the rank order of ligand affinity did not resemble that of a P2Y receptor (2-MeSATP having extremely low affinity) and fl,y-methyleneATP at 10-4 M abolished the high-affinity binding sites; the authors concluded that non-receptor sites were contributing to the high number of binding sites found. A major difference in the binding protocol which we have used is the complete absence here of magnesium and calcium, which are necessary for binding and catalysis at many ecto-enzymes using nucleotides such as ecto-ATPases (Culic et al, 1990;Ziganshin et al, 1995). Thus, nucleotide binding to such sites on cochlear hair cells has been shown to be decreased by 74% by the removal of divalent cations (Mockett et al, 1994).…”

Section: Resultsmentioning

confidence: 99%

The P2Y purinoceptor in rat brain microvascular endothelial cells couple to inhibition of adenylate cyclase

Webb

Feolde

Vigne

et al. 1996

British J Pharmacology

100

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“…ITP is, like the other nucleoside triphosphates, an equally efficient substrate for ecto-ATPase. This property distinguishes the enzyme from most of the other ATPases (Culic et al, 1990). When ATP was substituted by ITP in an assay that contained 141Ce3+ as capturing agent (Fig.…”

Section: Resultsmentioning

confidence: 99%

Autoradiography-based cytochemical detection of ecto-ATPase, ecto-ADPase, 5?-nucleotidase, and extracellular adenosine production, employing 141Ce3+ as a capturing agent

et al. 1995

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A method for the visualization of the ecto-nucleotidase enzyme activities present on the cell surface, employing 141Ce3+ as a capturing and labelling agent, is described. Phosphate ions precipitated at the cell surface can be detected by coating the cells with an autoradiographic emulsion, followed by light microscopical inspection of the formed silver grains. The activities of ecto-ATPase, ecto-ADPase and 5'-nucleotidase were detected by this approach in four different cell lines. Parallel biochemical measurements of the activities of the corresponding enzymes were carried out in order to validate, evaluate, and optimize the cytochemical detection. The finding that Ce3+ ions are inhibitory to ecto-ATPase provided evidence for the necessity of carefully establishing appropriate reaction conditions for the cytochemical determination of ecto-nucleotidases. The application of this method to the indirect detection of extracellular adenosine production from substrates like ATP has also been documented. It allows a cytochemical determination of adenosine formed through cascade nucleotide dephosphorylation. This newly described method is of high sensitivity and potentially of value for a variety of applications, including not only cytochemistry but also cell biology, and molecular biology studies.

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The stepwise hydrolysis of adenine nucleotides by ectoenzymes of rat renal brush-border membranes

Cited by 37 publications

References 40 publications

Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication.

Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication.

The P2Y purinoceptor in rat brain microvascular endothelial cells couple to inhibition of adenylate cyclase

Autoradiography-based cytochemical detection of ecto-ATPase, ecto-ADPase, 5?-nucleotidase, and extracellular adenosine production, employing 141Ce3+ as a capturing agent

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