FIGURE 4.

Effect of prolonged incubation of cells in the presence of endogenous NO. A, detection of oxygen consumption (top trace), cytochrome c redox state (middle trace), and NO in the medium (bottom trace) after the addition of 500 μm l-arginine to HEK293 cells transfected with an NO synthase. After different time intervals, the specific NO synthase inhibitor SEITU (1 mm) was added, and respiration was reinitiated after complete disappearance of NO from the medium. The rate of oxygen consumption was measured and calculated as a percentage of the oxygen consumption prior to anaerobiosis. B, dependence of the rate of oxygen consumption on the duration of incubation in the presence of NO.