Characterization of ATP and ADP hydrolysis activity in rat gastric mucosa.
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 microM) inhibited ATP and ADP hydrolysis at all concentrations tested. Orthovanadate slightly inhibited (15%) Mg2+ and Ca2+ ATP/ADPase at 100 microM. 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.
Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, RS, Brazil.
Lucielli
L
Savegnago
Cristina W
CW
Nogueira
Roselei
R
Fachinetto
Joao Batista Teixeira
JB
Rocha
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001081:Apyrase / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D019810:Sodium Azide / Q000494:pharmacology; D013379:Substrate Specificity; D013498:Suramin / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D015703:Antigens, CD; D004791:Enzyme Inhibitors; D014638:Vanadates; D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D019810:Sodium Azide; D001081:Apyrase; C067869:CD39 antigen; D008274:Magnesium; D002118:Calcium