Mitochondrial dysfunction is responsible for the intestinal calcium absorption inhibition induced by menadione.
Menadione (MEN) inhibits intestinal calcium absorption by a mechanism not completely understood. The aim of this work was to find out the role of mitochondria in this inhibitory mechanism. Hence, normal chicks treated with one i.p. dose of MEN were studied in comparison with controls. Intestinal calcium absorption was measured by the in situ ligated intestinal segment technique. GSH, oxidoreductase activities from the Krebs cycle and enzymes of the antioxidant system were measured in isolated mitochondria. Mitochondrial membrane potential was measured by a flow cytometer technique. DNA fragmentation and cytochrome c localization were determined by immunocytochemistry. Data indicate that in 30 min, MEN decreases intestinal Ca(2+) absorption, which returns to the control values after 10 h. GSH was only decreased for half an hour, while the activity of malate dehydrogenase and alpha-ketoglutarate dehydrogenase was diminished for 48 h. Mn(2+)-superoxide dismutase activity was increased in 30 min, whereas the activity of catalase and glutathione peroxidase remained unaltered. DNA fragmentation and cytochrome c release were maximal in 30 min, but were recovered after 15 h. In conclusion, MEN inhibits intestinal Ca(2+) absorption by mitochondrial dysfunction as revealed by GSH depletion and alteration of the permeability triggering the release of cytochrome c and DNA fragmentation.
Laboratorio Dr. Fernando Cañas, Catedra de Bioquimica y Biologia Molecular, Facultad de Ciencias Medicas, Universidad Nacional de Cordoba, Pabellon Argentina, 2do. Piso, Ciudad Universitaria, 5000 Cordoba, Argentina.
Ana M
AM
Marchionatti
Adriana V
AV
Perez
Gabriela E
GE
Diaz de Barboza
Beatriz M
BM
Pereira
Nori G
NG
Tolosa de Talamoni
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002645:Chickens; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology; D010088:Oxidoreductases / Q000378:metabolism; D024483:Vitamin K 3 / Q000494:pharmacology*
D024483:Vitamin K 3; D045304:Cytochromes c; D010088:Oxidoreductases; D002118:Calcium