Fig 2: Increased fibrosis, ERS and Warburg effect and decreased CSE expression and left atrial function were found in AF patients compared with SR patients. (A) H2S content was determined by Methylene blue method in the LAA of patients with SR or AF (n = 6 in each group). (B) Representative Western blotting and relative densitometry analysis of CSE, CBS, 3-MST, PDK-4, LDHA, PDH, ATF-4, CHOP, caspase-12 and GAPDH in the LAA of patients with SR or AF (n = 6 in each group). (C) Western blotting was used to analyze the protein levels of p-PERK and t-PERK in the LAA of patients with SR or AF (n = 6 in each group). (D) Western blotting was used to analyze the protein levels of p-elf2a and t-elf2a in the LAA of patients with SR or AF (n = 6 in each group). (E) Lactate acid was determined by kit analysis in the LAA of patients with SR or AF (n = 6 in each group). Blue staining with representative Masson staining (scale bar = 50 µm) and quantification of atrial fibrosis (n = 6 in each group, with =40 fields in each group) were used in the (F) AF group and (G) SR group. (H) Western blotting was used to analyze the protein levels of MMP-9 and GAPDH in the LAA of patients with SR or AF (n = 6 in each group). Representative RT-PCR and relative densitometry analysis of (I) collagen Ia and (J) collagen IIIa in the LAA of patients with SR or AF (n = 6 in each group). Left atrial function was measured by color Doppler echocardiography (K) LAESVI, (L) LAEF and (M) LAFI (n = 6 in each group) in the patients with SR or AF during the echocardiographic studies. **p < 0.01 VS AF. A Student’s t-test was used for each of these comparisons between AF and SR groups.

Fig 3: NaHS attenuated the Warburg effect and ERS in HL-1 cells under Ang II treatment. Representative Western blotting and relative densitometry analysis of (A) CSE with GAPDH as a loading control induced by Ang-II concentration in the HL-1 cell of the indicated groups (n = 6 in each group). (B) Detection of CSE activity by methylene blue assay in the HL-1 cell of the indicated groups (n = 6 in each group). CCK-8 was used to detect the changes in HL-1 cell viability induced by Ang II at different times (C) (n = 6 in each group). Representative Western blotting and relative densitometry analysis of (F) p-PERK with t-PERK as the loading control and (H) p-elF2a with t-elF2a as the loading control and (D) LDH, (E) PDK-4, (G) ATF 4, (I) CHOP and (J) caspase12 with GAPDH as the loading control in the HL-1 cell of the indicated groups (n = 6 in each group). Lactate acid (K) and glucose consumption (L) and the production of ATP (M) were determined by kit analysis in the HL-1 cell of the indicated groups (n = 6 in each group). **p < 0.01 VS Control, and p < 0.01 VS Ang II. Groups were compared using one-way analysis of variance (ANOVA) (Tukey’s) in (A–J).

Fig 4: NaHS inhibits left atrial remodeling induced by Ang II in SD rats and is associated with the inhibition of the Warburg effect and ERS. (A) Representative Western blotting and relative densitometry analysis of CSE, 3-MST and CBS with GAPDH as the loading control in the rats left atrial tissue of the indicated groups. (n = 6 in each group). (B) H2S content was determined by Methylene blue method in the rats plasma of the indicated groups (n = 6 in each group). Blue staining with representative Masson staining (scale bar = 50 µm) and quantification of atrial fibrosis (n = 6 in each group, with =40 fields in each group) were used in the (C) Sham group, (D) Ang II group, (E) NaHS + Ang II group, (F) DCA + Ang II group, (G) 4-PBA + Ang II group, (H) NaHS group, (I) DCA group and (J) 4-PBA group. (K) Representative Western blotting and relative densitometry analysis of MMP-9 with GAPDH as the loading control in the rats left atrial tissue of the indicated groups (n = 6 in each group). Representative RT-PCR and relative densitometry analysis of (L) Collagen Ia and (M) Collagen IIIain the rats left atrial tissue of the indicated groups (n = 6 in each group). (N) ARPS was performed via the esophagus, and AF episodes and duration were recorded in the rats indicated groups. Electrophysiological analysis of numbers of AF episodes (O) and durations of AF (P), AERP (Q) and AERPd (R) in the rats indicated groups during the electrophysiological studies (n = 6 in each group). Left atrial function was measured by color Doppler echocardiography (S) LAESVI, (T) LAEF, and (U) LAFI in the rats indicated groups during the echocardiographic studies (n = 6 in each group). **p < 0.01 VS Control, and p < 0.01 VS Ang II, #p < 0.05 VS Ang II. Groups were compared using one-way analysis of variance (ANOVA) (Tukey’s) in C to M and P to U, Fisher’s exact test was used to compare groups in O, and Student’s t-test was used to compare groups in (A,B).