Each compound reveals a different component of oxygen consumption. Oligomycin inhibits ATP synthase, so the resulting change distinguishes respiration linked to ATP production from proton leak. FCCP uncouples respiration and exposes maximal respiratory capacity. Rotenone plus antimycin A blocks the electron transport chain, allowing non-mitochondrial respiration to be identified and separated from mitochondrial oxygen consumption.
Spare respiratory capacity is derived by comparing maximal respiration after FCCP with the cell’s basal respiration. It indicates how much additional respiratory output remains available when energy demand increases. In immune or infected-cell experiments, differences in this parameter can help characterize whether metabolic reprogramming changes the cell’s ability to respond to increased energetic demands.
The assay assigns oxygen consumption to functional categories by comparing measurements across the inhibitor sequence. Oligomycin-related changes estimate respiration associated with ATP synthesis and help identify proton leak, while rotenone and antimycin A establish the non-mitochondrial component. Together with basal and FCCP-stimulated values, these comparisons provide a profile rather than a single respiration measurement.
Sequential addition creates a controlled series of respiratory states in the same living-cell measurement. Basal respiration is recorded before mitochondrial modulation, ATP synthase inhibition tests the contribution of ATP production, uncoupling challenges the system, and electron transport chain blockade defines the residual signal. This order supports calculation of multiple related metabolic parameters from one assay.
The workflow uses living cells and extracellular flux analysis to record oxygen consumption while mitochondrial modulators are introduced sequentially. Measurements begin under basal conditions, followed by oligomycin, FCCP, and then rotenone with antimycin A. The resulting oxygen-consumption profile is used to calculate basal and maximal respiration, ATP-linked respiration, proton leak, spare capacity, and non-mitochondrial respiration.
Researchers can compare respiration profiles in immune cells exposed to pathogens or inflammatory stimuli, or examine how infection changes host-cell metabolism. Shifts in basal respiration, maximal capacity, ATP-linked respiration, proton leak, or spare capacity provide functional evidence of metabolic reprogramming. These measurements help connect cellular energy production with host responses and immune-cell activity.