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Cell Biology International (2005) 29, 559–566 (Printed in Great Britain)

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Characterization of ATP and ADP hydrolysis activity in rat gastric mucosa

Lucielli Savegnago, Cristina W. Nogueira, Roselei Fachinetto and Joao Batista Teixeira Rocha^*

Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, RS, Brazil

Abstract

The degradation of nucleotides is catalyzed by the family of enzymes called nucleoside triphosphate diphosphohydrolases (NTPDases). The aim of this work was to demonstrate the presence of NTPDase in the rat gastric mucosa. The enzyme was found to hydrolyze ATP and ADP at an optimum pH of 8.0 in the presence of Mg²⁺ and Ca²⁺. The inhibitors ouabain (0.01–1 mM), N-ethylmaleimide (0.01–4 mM), levamisole (0.10–0.2 mM) and Ap5A (0.03 mM) had no effect on NTPDase 1 activity. Sodium azide (0.03–30 mM), at high concentrations (>0.1 mM), caused a parallel hydrolysis inhibition of ATP and ADP. Suramin (50–300 μM) inhibited ATP and ADP hydrolysis at all concentrations tested. Orthovanadate slightly inhibited (15%) Mg²⁺and Ca²⁺ ATP/ADPase at 100 μM. Lanthanum decreased Mg²⁺ and Ca²⁺ ATP/ADPase activities. The presence of NTPDase as ecto-enzyme in the gastric mucosa may have an important role in the extracellular metabolism of nucleotides, suggesting that this enzyme plays a role in the control of acid and pepsin secretion, mucus production, and contractility of the stomach.

Key words: NTPDase, Stomach, Extracellular ATP, Ectonucleotidases, Apyrase.

^*Corresponding author. Tel.: +55 55 220 8140; fax: +55 55 220 8978.

Received 16 September 2004/19 January 2005; accepted 8 March 2005