Drug-induced mitochondrial dysfunction is of major clinical interest. An NMR-compatible bioreactor system was used to investigate the oxygen consumption of HepG2 cells by measuring T1 of perflubron. The oxygen consumption was measured by stopping the perfusion. This resulted in a reduction of the oxygen concentration from (19.29 ± 0.96)% to (11.41 ± 0.92)% in 104.24 min. Our results might allow for detecting a drug-induced mitochondrial dysfunction of cells in a well-controlled environment by using the two compartments of the bioreactor.