title: Enzymes that hydrolyze adenine nucleotides in lymphocytes and platelets of immunosuppressed rats.
abstract: NTPDase (EC 3.6.1.5) is an enzyme that hydrolyzes extracellular nucleoside tri-and/ or diphosphates to form ATP, which can serve as a substrate for ecto-5'- nucleotidase (EC 3.1.3.5), releasing adenosine, an inhibitor of platelet aggregation and an immunosuppressant agent. In this study, the activity of enzymes that hydrolyze adenine nucleotides was investigated in lymphocytes and platelets of immunosuppressed rats. NTPDase and ecto-5'-nucleotidase activities were determined by colorimetric assay with quantification of the inorganic phosphate released. A significant increase in NTPDase activity was observed in lymphocytes (about 30% in ATP hydrolysis and 80% in ADP hydrolysis, at p<0.05 and p<0.01, respectively). In platelets, there was a significant increase in 5'-nucleotidase activity in immunosuppressed rats (p<0.01) when compared with controls. These results suggest that the hydrolysis of adenine nucleotides is modified in the immunosuppressed state, possibly to compensate for alterations that occur and to avoid the adverse effects of therapy.
authors.affiliation: Curso de Farmácia, Centro Universitário Franciscano, 97010-032, Santa Maria, RS, Brazil.
authors.forename: Eder M
authors.initials: EM
authors.lastname: Saucedo
authors.forename: Renata S
authors.initials: RS
authors.lastname: Pereira
authors.forename: Gabriela M
authors.initials: GM
authors.lastname: Barbosa
authors.forename: Vanessa
authors.initials: V
authors.lastname: Battisti
authors.forename: Claudio A M
authors.initials: CA
authors.lastname: Leal
authors.forename: Juliana
authors.initials: J
authors.lastname: Fleck
authors.forename: Roberto C V
authors.initials: RC
authors.lastname: Santos
authors.forename: Vera M
authors.initials: VM
authors.lastname: Morsch
authors.forename: Maria R C
authors.initials: MR
authors.lastname: Schetinger
authors.forename: Daniela Bitencourt Rosa
authors.initials: DB
authors.lastname: Leal
mesh_terms: D015720:5'-Nucleotidase / Q000502:physiology*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D001081:Apyrase / Q000502:physiology*; D001792:Blood Platelets / Q000201:enzymology*; D006801:Humans; D006868:Hydrolysis; D007108:Immune Tolerance; D008214:Lymphocytes / Q000201:enzymology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015703:Antigens, CD; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D015720:5'-Nucleotidase; D001081:Apyrase; C067869:CD39 antigen