L-Lactate Protects Skin Fibroblasts against Aging-Associated Mitochondrial Dysfunction via Mitohormesis

Figure 4

Markers of mitochondrial dysfunction in high-passage fibroblasts. (a) Basal (black bars) and maximal (grey bars; after uncoupling with FCCP) respiration of fibroblasts in complete media. (b) Relative production of H₂O₂ from fibroblasts measured by Amplex Red. (c) Relative rate of secretion of lactate into culture media from fibroblasts. (d) mtDNA copy number per cell as a measure of mitochondrial abundance in fibroblasts. Relative expression (normalized to GAPDH mRNA) of (e) TFAM and (f) POLG mRNAs as a measure of PGC1α activity in fibroblasts (control fibroblasts: passage 2 (CTRL); control fibroblasts: passage 18 (L0); fibroblasts cultured in constant 5 mM L-lactate: passage 18 (LC); and fibroblasts exposed to twice a week pulses of 5 mM L-lactate: passage 18 (LI); ^∗significantly different from L0; ; ^#significantly different from CTRL; ).

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