title: Calcium modulates the ATP and ADP hydrolysis in human placental mitochondria.
abstract: This study evaluated the effect of Ca2+ on the extramitochondrial hydrolysis of ATP and ADP by the extramitochondrial ATPase in isolated mitochondria and submitochondrial particles (SMPs) from human term placenta. The effect of different oxidizable substrates on the hydrolysis of ATP and ADP in the presence of sucrose or K+ was evaluated. Ca2+ increased phosphate release from ATP and ADP, but this stimulation showed different behavior depending on the oxidizable substrate present in the incubation media. Ca2+ stimulated the hydrolysis of ATP and ADP in the presence of sucrose. However, Ca2+ did not stimulate the hydrolysis of ADP in the medium containing K+. Ca2+ showed inhibition depending on the respiratory substrate. This study suggests that the energetic state of mitochondria controls the extramitochondrial ATPase activity, which is modulated by Ca2+ and respiratory substrates.
authors: Departamento de Bioquimica, Facultad de Medicina, UNAM Apdo., Postal 70-159, 04510, Mexico City, Mexico. fedem@servidor.unam.mx
authors: Federico
authors: F
authors: Martínez
authors: Aida
authors: A
authors: Uribe
authors: M Teresa
authors: MT
authors: Espinosa-García
authors: Oscar
authors: O
authors: Flores-Herrera
authors: Cecilia
authors: C
authors: García-Pérez
authors: Rebeca
authors: R
authors: Milán
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007656:Ketoglutaric Acids / Q000494:pharmacology; D008293:Malates / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy
chemical_list: D007656:Ketoglutaric Acids; D008293:Malates; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; C030298:malic acid; D000255:Adenosine Triphosphate; D002118:Calcium