Loss of Myeloid Differentiation Protein 1 Promotes Atrial Fibrillation in Heart Failure with Preserved Ejection Fraction

Figures

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  Figure 1. Analysis of surface electrocardiograph in wide‐type (WT) and myeloid differentiation protein 1 knock‐out mice 4 weeks after saline or aldosterone infusion. (A) A representative trace of the surface electrocardiography. RR interval, P wave duration, PR interval, QRS duration, and QTc interval were indicated as an arrow. (B) Surface electrocardiography parameters (n = 8). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. WT‐Sal group and # P < 0.05 vs. WT‐Aldo group.

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  Figure 2. The electrophysiological properties of the atrial in wide‐type (WT) and myeloid differentiation protein 1 knock‐out mice 4 weeks after saline or aldosterone infusion. (A–D) Intra‐atrial conduction time (IACT) and effective refractory period (ERP) of the left atrium evaluated in the study using isolated perfused heart mice (n = 8). (E) Representative electrograms of atrial fibrillation (AF) induction after atrial burst pacing in the isolated perfused heart using Langendorff apparatus in a knock‐out (KO)‐Aldo mouse. (F,G) Inducibility and duration of AF in the study using isolated perfused heart (n = 12–13). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. wild‐type (WT)‐Sal group, # P < 0.05 vs. WT‐Aldo group, and § P < 0.1 vs. WT‐Aldo group.

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  Figure 3. Myocardial fibrosis in wild‐type (WT) and Myeloid differentiation protein 1 (MD1)‐knock‐out mice 4 weeks after saline or aldosterone infusion. (A) Representative western blots of MD1 expression in left atrial tissues from WT and MD1‐KO mice (n = 6). (B) Representative Masson trichrome staining. Original magnification ×400; (C) myocardial fibrosis area (n = 4); and (D,E) representative western blots and statistical analysis of the fibrosis‐related proteins levels (n = 4). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. WT‐Sal group and # P < 0.05 vs. WT‐Aldo group.

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  Figure 4. Myocardial inflammation in wild‐type (WT) and myeloid differentiation protein 1 knock‐out mice 4 weeks after saline or aldosterone infusion. (A,B) Representative western blots and statistical analysis of the inflammation‐related protein levels (n = 4). (C,D) Representative western blots and statistical analysis of p65, P‐p65, inhibitor of kappa B (IκBα), and P‐IκBα (n = 4). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. WT‐Sal group and # P < 0.05 vs. WT‐Aldo group.

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  Figure 5. Expression of calcium handling regulatory proteins in wild‐type (WT) and and myeloid differentiation protein 1 knock‐out mice 4 weeks after saline or aldosterone infusion. (A,B) Representative western blots and statistical analysis of ryanodine receptor 2 (RyR2) phosphorylation at Ser2814 and RyR2 phosphorylation at Ser2808, RyR2, and GAPDH (n = 4). (C,D) Representative western blots and statistical analysis of sarcoplasmic reticulum Ca2+‐ATPase 2a (SERCA2a) and phospholamban (PLB) phosphorylation at Thr17, PLB, sodium/calcium exchanger (NCX), and GAPDH (n = 4). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. WT‐Sal group and # P < 0.05 vs. WT‐Aldo group.

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  Figure 6. Myeloid differentiation protein 1 (MD1) regulates toll‐like receptor 4 (TLR4)/calmodulin‐dependent protein kinase II (CaMKII) signalling in in vivo and in vitro experiments. (A,B) Representative western blots and statistical analysis of TLR4, CaMKII, and P‐CaMKII in wild‐type (WT) and MD1‐knock‐out (KO) mice 4 weeks after saline or aldosterone infusion (n = 4). Data are expressed as mean ± standard error of the mean, * P < 0.05 vs. WT‐Sal group and # P < 0.05 vs. WT‐Aldo group. (C, D) Representative western blots and statistical analysis of MD1, TLR4, P‐CaMKII, CaMKII, P‐p65, and p65 in aldosterone‐induced H9C2 cell (n = 4). Data are expressed as mean ± standard error of the mean. * P < 0.05 vs. Control, # P < 0.05 vs. Aldo, and & P < 0.05 vs. Ad‐ShMD1.