title: ATP and ADP hydrolysis in cell membranes from rat myometrium.
abstract: Extracellular nucleotides affect female reproductive functions, fertilization, and pregnancy. The aim of this study was to investigate biochemical characteristics of ATP and ADP hydrolysis and identify E-NTPDases in myometrial cell membranes from Wistar albino rats. The apparent K (m) values were 506.4 ± 62.1 and 638.8 ± 31.3 μM, with a calculated V (max) (app) of 3,973.0 ± 279.5 and 2,853.9 ± 79.8 nmol/min/mg for ATP and ADP, respectively. The enzyme activity described here has common properties characteristic for NTPDases: divalent cation dependence; alkaline pH optimum for both substrates, insensitivity to some of classical ATPase inhibitors (ouabain, oligomycine, theophylline, levamisole) and significant inhibition by suramine and high concentration of sodium azides (5 mM). According to similar apparent K(m) values for both substrates, the ATP/ADP hydrolysis ratio, and Chevillard competition plot, NTPDase1 is dominant ATP/ADP hydrolyzing enzyme in myometrial cell membranes. RT-PCR analysis revealed expression of three members of ectonucleoside triphosphate diphosphohydrolase family (NTPDase 1, 2, and 8) in rat uterus. These findings may further elucidate the role of NTPDases and ATP in reproductive physiology.
authors.affiliation: Department of Molecular Biology and Endocrinology, Institute of Nuclear Sciences VINČA, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia. mmilosevic@vinca.rs
authors.forename: Maja
authors.initials: M
authors.lastname: Milošević
authors.forename: Snježana
authors.initials: S
authors.lastname: Petrović
authors.forename: Nataša
authors.initials: N
authors.lastname: Veličković
authors.forename: Ivana
authors.initials: I
authors.lastname: Grković
authors.forename: Marija
authors.initials: M
authors.lastname: Ignjatović
authors.forename: Anica
authors.initials: A
authors.lastname: Horvat
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001081:Apyrase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D006868:Hydrolysis; D007700:Kinetics; D009215:Myometrium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015703:Antigens, CD; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C027201:ectoATPase; C518947:nucleoside triphosphate diphosphohydrolase 8, rat; D001081:Apyrase; C067869:CD39 antigen