Nicotinamide adenine dinucleotides permeate through mitochondrial membranes in human Epstein-Barr virus-transformed lymphocytes.
Human cultured cells are widely used for the investigation of respiratory chain disorders. Oxidative properties are generally investigated by means of polarographic studies carried out on detergent-permeabilized cells. By studying the oxidative properties of Epstein- Barr virus-transformed B lymphocytes, we found that the respiration was significantly decreased after 3-4 days of cell culture. Simultaneously, we observed decreased NAD(+)-dependent oxidations (malate, glutamate, pyruvate) that became dependent upon the addition of exogenous NAD+. The effect of NAD+ was shown to be related to an influx of catalytic amount of NAD+ into the mitochondrial matrix. A full ability to oxidize NAD(+)-dependent substrates was restored less than 2 h after a change of the culture medium. These observations suggested: (a) the occurrence of fluxes of catalytic amounts of NAD+ through the mitochondrial inner membrane in human cells; (b) an early control of mitochondrial metabolism by matrix NAD+ content in cells grown under limiting growth conditions; (c) the possible confusion between complex I deficiency and a decrease content of matrix NAD+ when using human cultured cells.
Rustin
P
P
Unité de Recherches sur les Handicaps Génétiques de l' Enfant, INSERM U-393, Hôpital des Enfants-Malades, Paris, France.
Chretien
D
D
Parfait
B
B
Rötig
A
A
Munnich
A
A
D001402:B-Lymphocytes / Q000378:metabolism* / Q000648:ultrastructure / Q000821:virology; D001692:Biological Transport; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D004854:Herpesvirus 4, Human; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D009243:NAD / Q000378:metabolism*; D010539:Permeability
D009243:NAD