Muscular changes in animal models of heart failure with preserved ejection fraction: what comes closest to the patient?

Abstract

Aims: Heart failure with preserved ejection fraction (HFpEF) is associated with reduced exercise capacity elicited by skeletal muscle (SM) alterations. Up to now, no clear medical treatment advice for HFpEF is available. Identification of the ideal animal model mimicking the human condition is a critical step in developing and testing treatment strategies. Several HFpEF animals have been described, but the most suitable in terms of comparability with SM alterations in HFpEF patients is unclear. The aim of the present study was to investigate molecular changes in SM of three different animal models and to compare them with alterations of muscle biopsies obtained from human HFpEF patients.

Methods and results: Skeletal muscle tissue was obtained from HFpEF and control patients and from three different animal models including the respective controls-ZSF1 rat, Dahl salt-sensitive rat, and transverse aortic constriction surgery/deoxycorticosterone mouse. The development of HFpEF was verified by echocardiography. Protein expression and enzyme activity of selected markers were assessed in SM tissue homogenates. Protein expression between SM tissue obtained from HFpEF patients and the ZSF1 rats revealed similarities for protein markers involved in muscle atrophy (MuRF1 expression, protein ubiquitinylation, and LC3) and mitochondrial metabolism (succinate dehydrogenase and malate dehydrogenase activity, porin expression). The other two animal models exhibited far less similarities to the human samples.

Conclusions: None of the three tested animal models mimics the condition in HFpEF patients completely, but among the animal models tested, the ZSF1 rat (ZSF1-lean vs. ZSF1-obese) shows the highest overlap to the human condition. Therefore, when studying therapeutic interventions to treat HFpEF and especially alterations in the SM, we suggest that the ZSF1 rat is a suitable model.

Keywords: Animal models; Heart failure with preserved ejection fraction; Skeletal muscle.

Figure 1

An overview of the study design. Skeletal muscle biopsies (Quadriceps muscle) obtained from heart failure with preserved ejection fraction (HFpEF) patients and healthy controls were compared with skeletal muscle tissue [extensor digitorum longus (EDL) muscle] obtained from three different HFpEF animal models: ZSF1 rat model (control: ZSF1‐lean rats; HFpEF: ZSF1‐obese rats, 31 weeks); Dahl salt‐sensitive (DSS) rats [control: low salt (0.3%) in drinking water, HFpEF: high salt (8%) in drinking water for 21 weeks]; TAC/DOCA mouse model (control: sham operated mouse, HFpEF: TAC operations with DOCA releasing pellet for 4 weeks). TAC, transverse aortic constriction; DOCA, deoxycorticosterone acetate.

Figure 2

Protein expression of MuRF1 (A), MafBx (B), protein ubiquitinylation (C) and LC3 (D) was quantified by western blot analysis in skeletal muscle tissue obtained from humans [heart failure with preserved ejection fraction (HFpEF) and controls] and three different HFpEF animal models [ZSF1, DSS, transverse aortic constriction/deoxycorticosterone acetate (TAC/DOCA)]. Values are shown as mean ± SEM expressed as x‐fold vs. control. Statistical comparison was made between control and HFpEF of the respective model. Representative examples of Western blots are depicted on top of the figure (C, control; H, HFpEF).

Figure 3

Protein expression of myosin heavy chain (A), actin (B), and telethonin (C) was quantified by western blot analysis in skeletal muscle tissue obtained from humans [heart failure with preserved ejection fraction (HFpEF) and controls] and three different HFpEF animal models [ZSF1, DSS, and transverse aortic constriction/deoxycorticosterone acetate (TAC/DOCA)]. Values are shown as mean ± SEM expressed as x‐fold vs. control. Statistical comparison was made between control and HFpEF of the respective model. Representative examples of Western blots are depicted on top of the figure (C, control; H, HFpEF).

Figure 4

Protein expression of porin (A) and PGC1a (B) was quantified by western blot analysis in skeletal muscle tissue obtained from humans [heart failure with preserved ejection fraction (HFpEF) and controls] and three different HFpEF animal models [ZSF1, Dahl salt‐sensitive (DSS), transverse aortic constriction/deoxycorticosterone acetate (TAC/DOCA)]. In addition, specific enzyme activity of succinate dehydrogenase (SDH) (C), malate dehydrogenase (MDH) (D), creatine kinase (CK) (E) and lactate dehydrogenase (LDH) (F) was measured. Values are shown as mean ± SEM expressed as x‐fold vs. control. Statistical comparison was made between control and HFpEF of the respective model. Representative examples of Western blots are depicted on top of the figure (C, control; H, HFpEF).

Figure 5

Protein expression of NADPH oxidase subunit gp91^phox (A) SOD1 (B), SOD2 (C) and TNFα (D) was quantified by western blot analysis in skeletal muscle tissue obtained from humans [heart failure with preserved ejection fraction (HFpEF) and controls] and three different HFpEF animal models [ZSF1, succinate dehydrogenase (DSS), transverse aortic constriction surgery/deoxycorticosterone acetate (TAC/DOCA)]. Values are shown as mean ± SEM expressed as x‐fold vs. control. Statistical comparison was made between control and HFpEF of the respective model. Representative examples of Western blots are depicted on top of the figure (C, control; H, HFpEF).