FIGURE 6.

The effect of gentamicin on respiratory parameters in isolated rat kidney mitochondria. (A) Succinate addition (+) in the gentamicin condition causes a much larger O₂ flux response than in the control. Subsequent addition of 1 μM CCCP (++), an uncoupler of the ETC, causes O₂ flux to rise significantly in the control (green), whereas a greatly reduced rise is seen when pre-incubated with gentamicin (red). (B) Quantification of the results shows that gentamicin causes a concentration-dependent decrease in the RCR of isolated kidney mitochondria. (C) Succinate is added to the chamber to initiate respiration (+), generating a proton gradient and consequent hyperpolarization of the mitochondrial membrane. When gentamicin is added to the chamber in 1 mM increments (↓) there is a sudden increase in safranin signal, suggesting that gentamicin is dissipating the proton gradient and depolarizing the MtMP. (D) Shows H₂O₂ levels detected over a period of 10 min, with the rates of production and overall concentrations plotted. Solid lines display concentrations, dashed lines display rates. Green is control, red is gentamicin. Following 10 mM succinate addition (+), the endogenous formation of ROS is inhibited by gentamicin (N = 1, n = 1).