Fig. 4

Biphasic effect of C18:1AC on mitochondrial respiration. Respiration of murine cardiac mitochondria supplied with a glutamate/malate (G/M) or b pyruvate/malate (P/M) as substrates, exposed to 12.5 or 25 µM C18:1AC (n = 3–7 mouse hearts). Mitochondrial respiration states: State 2 = basal state without compounds; State 3 = activated state with ATP production; State 4 = no ATP production. Respiratory state 3 obtained by stimulating ATP synthase with saturating (1 mM) ADP. State 4 induced by oligomycin (1.2 µM) to block ATP synthase and 2,4-dinitrophenol (DNP) to uncouple respiration. c Sequential addition of C18:1AC (5 µM each) during P/M respiration of human atrial mitochondria. d NAD(P)H autofluorescence of murine cardiac mitochondria supplied with P/M and ADP (1 mM), addition of 10, 25, or 100 µM C18:1AC. Cyanide (CN) added to inhibit complex IV, reducing NAD(P)H, preventing oxidation by the electron transport chain. Oligomycin and DNP added to induce complete oxidation of NAD(P)H. e Scheme of Krebs cycle and electron transport chain and potential mechanism of inhibition by C18:1AC. Two-way ANOVA plus Bonferroni´s post-test for multiple comparisons: ****p < 0.0001 for C18:1AC 12.5 µM vs. 25 µM; ^§§p < 0.01, ^§§§§p < 0.0001 for C18:1AC 12.5 µM vs. control; ^#p < 0.05, ^####p < 0.0001 for C18:1AC 25 µM vs. control; n number of hearts. α-KG α-ketoglutarate, AU arbitrary units, ADP adenosine diphosphate, DNP dinitrophenol, ETF electron transfer flavoprotein, OAA oxaloacetate, TMRM tetramethylrhodamine methyl ester