Calcium modulates the ATP and ADP hydrolysis in human placental mitochondria.
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.
Martínez
Federico
F
Departamento de Bioquimica, Facultad de Medicina, UNAM Apdo., Postal 70-159, 04510, Mexico City, Mexico. fedem@servidor.unam.mx
Uribe
Aida
A
Espinosa-García
M Teresa
MT
Flores-Herrera
Oscar
O
García-Pérez
Cecilia
C
Milán
Rebeca
R
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
D007656:Ketoglutaric Acids; D008293:Malates; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; C030298:malic acid; D000255:Adenosine Triphosphate; D002118:Calcium