Fig. 5.

ASIC1a mediates L-lactate-induced increase in mitochondrial respiration and suppresses mitochondrial ROS production.

Seahorse analysis (see Materials and Methods) was used to monitor mitochondrial respiration (OCR) with sequential additions of oligomycin (1 μM), FCCP (1 μM) + sodium pyruvate (5 mM), and a mix of rotenone/antimycin A (Ro/AA, 0.5 μM each), as indicated by the arrowheads, in media that contained or not D-, or L-lactate (5 mM);

(A) Representative OCR plots of WT neurons in regular medium that contained no lactate (Ctrl) or the indicated lactate isomer and CIN4;

(B) Quantification of maximal respiration as measured in (A) of WT neurons in regular medium (n = 6), and the medium that contained D- (n = 6) or L-lactate (n = 6), or L-lactate plus CIN4 (n = 6);

(C) Representative OCR plots of KO neurons in regular medium or medium that contained the indicated lactate isomer and CIN4;

(D) Quantification of maximal respiration as measured in (C) of KO in regular medium (Ctrl, n = 6) and media that contained the indicated D-lactate (n = 6), L-lactate (n-6), and L-lactate + CIN4 (n = 6);

(E) Representative OCR plots of WT and KO neurons in L -lactate containing medium;

(F) Quantification of maximal respiration as measured in (E) of WT (n = 6) and KO (n = 6) neurons;

(G) Representative OCR plots of WT and KO neurons in L-lactate/CIN4 containing medium (n = 6);

(H) Quantification of maximal respiration as measured in (G) of WT and KO neurons in L -lactate/CIN4 containing medium (n = 6 for each);

(I) Representative RoGFP fluorescence traces for redox changes in response to L-lactate, H₂O₂ and DTT added in the Ringer's solution in WT neurons untreated and treated with PcTX1;

(J) Quantification of R/R₀ (480/405) at 500s after the addition of L-lactate (100s) as in (I) for WT neurons untreated (n = 9) and treated with PcTX1 (n = 7);

(K) Schematic presentation of suggested pathway linking L-lactate to ASIC1a.

All summary graph data represent mean ± SD, *p < 0.05, **p < 0.01, ***p < 0.001.