Fig. 6

Cardiomyocytes uptake lactate via MCT1. A CFs were treated with or without Ang II after transfected with empty vector, sh-GCN5L1 and sh-MPC2 respectively. Relative quantification of the lactic acid concentration in the cell medium was detected n ≥ 4/group. B , C Cardiomyocytes were treated with different conditioned medium of CFs cultures. Representative immunoblot images showing LDHB, ANP and BNP protein expression (B). The quantification of these proteins (C) n = 5/group. D, E Representative images of cardiomyocytes treated with conditioned medium of CFs or lactate (4 × 10^− 3 mol/L) stained with immunofluorescent Mito Tracker Red (red), MCT1 (green) and DAPI (blue). Scale bar = 50 μm (D). Quantification of the relative fluorescence intensity (E) (n ≥ 4/group). The data are shown as the mean ± SEM. P values were calculated by one-way ANOVA. ^*p < 0.05, ^**p < 0.01. F , G Cardiomyocytes were treated with conditioned medium of CFs or lactate. Representative immunoblot images showing MCT1, ANP and MYH7 protein expression (F). The quantification of these proteins (G) (n = 3/group). H , I Schematic diagram showing isotope-tracing experiments (H). Cardiomyocytes were infected with empty vector or sh-MCT1. [U-¹³C₃]-l-lactate was added into culture media for 30 min. Then, tracing analysis from [U-¹³C₃]-l-lactate was performed. Intracellular abundance of citrate (M + 2), a-KG (M + 2), succinate (M + 2), fumarate (M + 2), Malate (M + 2) was calculated (I). J, K Cardiomyocytes were infected with empty vector or sh-MCT1, then stimulated with CM of CFs with Ang II treatment for 24 h. Representative immunoblot images showing ANP and BNP protein expression (J). The quantification of these proteins (K) (n ≥ 4/group). The data are shown as the mean ± SEM. P values were calculated by one-way ANOVA. ^*p < 0.05,^**, p < 0.01