Fig. 6

Enhanced oxidative metabolism in NK cells from trained versus untrained older adults. (A) Frequency of isolated NK cells (CD3⁻CD56+) in peripheral blood. (B,C) Representative Seahorse metabolic flux traces showing OCR and ECAR for NK cells from untrained (blue circles) and endurance-trained (green squares) donors. (D) Basal OCR. (E) Maximal OCR, measured after FCCP injection. (F) Spare respiratory capacity (maximal OCR – basal OCR). (G) Maximal ECAR. (H) OCR/ECAR ratio, indicating relative reliance on oxidative versus glycolytic metabolism. (I) ATP-linked OCR (basal OCR – oligomycin-inhibited OCR). (J) Proton leak (oligomycin‐inhibited OCR – non-mitochondrial respiration). Data are presented as mean ± SEM from n = 4 untrained and n = 5 endurance-trained donors. * P < 0.05 versus untreated control (Mann-Whitney U test). OCR, oxygen‐consumption rate; ECAR, extracellular acidification rate; FCCP, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone.