Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Oct 16:14:1237187.
doi: 10.3389/fphys.2023.1237187. eCollection 2023.

Volume overload impedes the maturation of sarcomeres and T-tubules in the right atria: a potential cause of atrial arrhythmia following delayed atrial septal defect closure

Zhuoya Dong #  1 , Dian Chen #  2 , Sixie Zheng #  2 , Zheng Wang  2 , Debao Li  2 , Yingying Xiao  3 , Sijuan Sun  4 , Lincai Ye  2   5   6 , Lisheng Qiu  2 , Yuqing Hu  7 , Haifa Hong  1   3
Affiliations

Volume overload impedes the maturation of sarcomeres and T-tubules in the right atria: a potential cause of atrial arrhythmia following delayed atrial septal defect closure

Zhuoya Dong et al. Front Physiol. .

Abstract

Introduction: Adult patients with atrial septal defects (ASD), the most common form of adult congenital heart disease, often die of arrhythmias, and the immaturity of cardiomyocytes contributes significantly to arrhythmias. ASD typically induces a left-to-right shunt, which then leads to the right atrium (RA) volume overload (VO). Whether or not VO contributes to RA cardiomyocyte immaturity and thereby causes arrhythmias in adult patients with ASD remains unclear. Methods: Here, we developed the first neonatal RA VO mouse model by creating a fistula between the inferior vena cava and abdominal aorta on postnatal day 7. RA VO was confirmed by increases in the mean flow velocity, mean pressure gradient, and velocity time integral across the tricuspid valve, and an increase in the RA diameter and RA area middle section. Results: We found that VO decreased the regularity and length of sarcomeres, and decreased the T-element density, regularity, and index of integrity of T-tubules in RA cardiomyocytes, suggesting that the two most important maturation hallmarks (sarcomere and T-tubules) of RA cardiomyocytes were impaired by VO. Accordingly, the calcium handling capacity of cardiomyocytes from postnatal day 21 (P21) RA was decreased by VO. VO caused a significant elongation of the PR interval. The expression of connexin 43 (Cx43) was decreased in RA VO. Moreover, gene ontology (GO) analysis of the downregulated genes in RA demonstrated that there was an abundance of enriched terms associated with sarcomeres and T-tubules exposed to VO. The results were further verified by qRT-PCR. Conclusions: In conclusion, the first neonatal RA VO mouse model was developed; furthermore, using this neonatal RA VO mouse model, we revealed that VO impeded RA sarcomere and T-tubule maturation, which may be the underlying causes of atrial arrhythmias in adult patients with ASD.

Keywords: atrial septal defects; atrium; maturation; sarcomere; transverse tubules; volume overload.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Abdominal aorta and inferior vena cava fistula creation and verification. (A) Timeline diagram of the experiment protocol. (B) Upper panel: Local anatomy of the abdominal aorta (AA) and inferior vena cava (IVC). Lower panel: Schematic of the fistula surgery. An illustration video can be found at: (https://www.ahajournals.org/doi/suppl/10.1161/JAHA.121.020854). (C) IVC manifested no pulsatile blood flow. (D) AA manifested pulsatile blood flow. (E) Fistula manifested pulsatile blood flow. (F) Quantification of the fistula peak velocity.
FIGURE 2
FIGURE 2
Verification of RA VO with H&E staining and organ weights. (A) Representative RA images. (B) Quantification of the RA area at the midpoint of the coronal section. (C–G) Quantification of body weight (BW), heart weight (HW), HW/BW ratio, lung weight, and lung weight/BW ratio in the sham and VO groups. n = 6, Student’s t-test. ns, no significance; **p < 0.01, ***p < 0.001, ****p < 0.0001.
FIGURE 3
FIGURE 3
Verification of RA VO with echocardiography and cardiac catheterization. (A) Representative echocardiography at the tricuspid levels. Note the sharp waveform in the VO group. (B) Quantification of tricuspid mean velocity (Vmean). (C) Quantification of the tricuspid mean pressure gradient (Pmean). (D) Quantification of the tricuspid velocity time integral (VTI). (E–H) Quantification of left ventricular ejection fractions (LVEFs), left ventricular end-systolic volumes (LVESVs), left ventricular end-diastolic volumes (LVEDVs), and right atrium diameters (RADs) in the sham and VO groups. (I, J) Quantification of right ventricular systolic pressures (RVSPs) and mean right ventricular pressures (mRVPs) in the sham and VO groups. n = 6, Student’s t-test. ns, no significance; *p < 0.05, **p < 0.01, ****p < 0.0001.
FIGURE 4
FIGURE 4
Impaired sarcomere and T-tubule maturation caused by VO. (A) Left panel: Representative sarcomere from the sham and VO groups. Sarcomeric α-actinin (SAA, white) staining, where arrow indicates one sarcomere. Right panel: Representative magnitude of fast Fourier transform (FFT) of cardiomyocytes shown in (A); the direct current (DC) component was defined as the transformed series at frequency 0, which represents the summation of signals of all pixels in the image; the major frequency was defined as the second highest peak; regularity was defined as the magnitude of the major frequency normalized to that of the DC component. (B) Quantification of sarcomere regularity and sarcomere length from cardiomyocytes in each group (n = 30), Mann–Whitney test. (C) Representative T-tubule image. The T-element (green) is highlighted (right panel). Scale bar, 25 μm. (D) Quantification of the T-element density from cardiomyocytes in each group (n = 30), Mann–Whitney test. (E) Quantification of T-tubule regularity from cardiomyocytes in each group (n = 30), Mann–Whitney test. (F) Quantification of the index of T-tubule integrity from cardiomyocytes in each group (n = 30), Mann–Whitney test. ****p < 0.0001.
FIGURE 5
FIGURE 5
Impaired electrophysiological activity of RA cardiomyocytes caused by VO. (A) Left panel: Representative calcium transient image of RA cardiomyocytes from sham and VO mice. Right panel: Plot representative of the calcium transient image of RA cardiomyocytes from sham and VO mice. (B) Quantification of the calcium transient amplitude (Amp) from cardiomyocytes of three hearts in each group (n = 30), Mann–Whitney test. (C) Quantification of the calcium transient time to peak from cardiomyocytes of three hearts in each group (n = 30), Mann–Whitney test. (D) Representative electrocardiogram of sham and VO mice. (E) Quantification of the P-wave amplitude, P-wave duration, and PR interval in mice in each group (n = 6). (F) Representative IHC image of connexin 43 (Cx43) from sham and VO RA. (G) Quantification of the Cx43 percentage in intercalated discs in mice in each group (n = 6). ns, no significance; *p < 0.05, ****p < 0.0001.
FIGURE 6
FIGURE 6
RNA-seq analysis of VO-induced downregulated genes in RA. (A) Volcano map of differentially expressed genes. Noted that there were 1,031 upregulated genes and 1,091 downregulated genes, which were then subjected to GO enrichment analysis and cluster analysis. (B) Cluster analysis of the 1,091 downregulated genes showed differences between groups and consistency within groups. (C) Top 20 enriched GO terms associated with sarcomeres. (D) Enriched GO terms associated with T-tubules.
FIGURE 7
FIGURE 7
Verification of the sarcomere- and T-tubule-associated genes enriched in the GO analysis of downregulated genes. (A) Ten representative sarcomere-associated genes enriched in the GO term of striated muscle cell development. (B) Ten representative T-tubule-associated genes enriched in the GO term of T-tubules.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Baumgartner H., De Backer J., Babu-Narayan S. V., Budts W., Chessa M., Diller G. P., et al. (2021). 2020 ESC Guidelines for the management of adult congenital heart disease. Eur. Heart J. 42, 563–645. 10.1093/eurheartj/ehaa554 - DOI - PubMed
    1. Berger F., Vogel M., Kramer A., Alexi-Meskishvili V., Weng Y., Lange P. E., et al. (1999). Incidence of atrial flutter/fibrillation in adults with atrial septal defect before and after surgery. Ann. Thorac. Surg. 68, 75–78. 10.1016/s0003-4975(99)00478-6 - DOI - PubMed
    1. Bray M. A., Sheehy S. P., Parker K. K. (2008). Sarcomere alignment is regulated by myocyte shape. Cell Motil. Cytoskelet. 65, 641–651. 10.1002/cm.20290 - DOI - PMC - PubMed
    1. Brida M., Chessa M., Celermajer D., Li W., Geva T., Khairy P., et al. (2022). Atrial septal defect in adulthood: A new paradigm for congenital heart disease. Eur. Heart J. 43, 2660–2671. 10.1093/eurheartj/ehab646 - DOI - PubMed
    1. Campostrini G., Windt L. M., van Meer B. J., Bellin M., Mummery C. L. (2021). Cardiac tissues from stem cells: new routes to maturation and cardiac regeneration. Circ. Res. 128, 775–801. 10.1161/CIRCRESAHA.121.318183 - DOI - PMC - PubMed

Grants and funding

This work was supported by the National Key R&D Program of China (No. 2019YFA0110401), the Shanghai Natural Science Foundation (Nos 22ZR147900 and 23ZR1441100), the National Natural Science Foundation of China (Nos 82270314, 82200309, and 82001835), the Key Discipline Group Development Fund of the Health and Family Planning Commission of Pudong New District (PWZxq2017-14), Shanghai Key Clinical Specialty (shslczdzk), the Biomedical and Engineering (Science) Interdisciplinary Study Fund of Shanghai Jiao Tong University (YG2019QNB03), and the Innovation Project of Distinguished Medical Team in Ningbo (2022020405).
-