Oxygen metabolism in human placenta mitochondria

BUSTAMANTE, J.; RAMIREZ-VELEZ, R; CZERNICZYNIEC, A; CICERCHIA, D; AGUILAR DE PLATA, AC; LORES ARNAIZ, S

JOURNAL OF BIOENERGETICS AND BIOMEMBRANES

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2014 vol. 46 p. 459 - 469

0145-479X

Due to the high metabolic demands of the placentaltissue during gestation, we decide to analyzed the mitochondrialbioenergetic functions in the human term placenta.Different mitochondrial morphological parameters, membranepotential and cardiolipin content were determined byflow cytometry. Oxygen uptake, hydrogen peroxide productionand cytochrome P450 content, were also measured. Someapoptotic mitochondrial proteins were also analyzed by westernblot. Two isolated mitochondrial fractions were observed:large/heavy and small/light with different functional characteristics.Oxygen uptake showed a respiratory control (RC) of3.4±0.3 for the heavy mitochondria, and 1.1±0.4 for lightmitochondria, indicating a respiratory dysfunction in the lightfraction. Good levels of polarization were detected in theheavy fraction, meanwhile the light population showed acollapsed ΔΨm. Increased levels of cytochrome P450, higherlevels of hydrogen peroxide, and low cardiolipin content weredescribed for the light fraction. Three pro-apoptotic proteinsp53, Bax, and cytochrome c were found increased in theheavy mitochondrial fraction; and deficient in the light fraction.The heavy mitochondrial fraction showed an improvedrespiratory function. This mitochondrial fraction, being probablyfrom cytotrophoblast cells showed higher content ofproteins able to induce apoptosis, indicating that these cellscan effectively execute an apoptotic program in the presenceof a death stimulus. Meanwhile the light and small organellesprobably from syncytiotrophoblast, with a low oxygen metabolism,low level ofΔΨm, and increased hydrogen peroxideproduction, may not actively perform an apoptotic processdue to their deficient energetic level. This study contributes tothe characterization of functional parameters of human placentamitochondria in order to understand the oxygen metabolismduring the physiological process of gestation.