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Abstract: TH-PO512

Detection of Na+ Stores in the Myocardium and Skeletal Muscle of DOCA Treated Mice Using 23Na-MRI

Session Information

Category: Fluid and Electrolytes

  • 901 Fluid and Electrolytes: Basic

Authors

  • Dahlmann, Anke, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
  • Linz, Peter, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
  • Perisic, Stojan, Max Planck Institute for medical research, Stuttgart, Germany
  • Tschesche, Jonas, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
  • Nagel, Armin M., Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
  • Titze, Jens, Duke - National University of Singapore, Singapore, Singapore
  • Bäuerle, Tobias, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
  • Kopp, Christoph, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
Background

Disturbances in Na+ homeostasis with accumulation of Na+ in tissue are present in salt sensitive hypertension. Tissue Na+ distribution could be recently visualized in vivo by 23Na-MRI. If Na+ accumulation occurs also in organs of the cardiovascular system is unknown. We hypothesized that the myocardium is able to absorb significant amounts of Na+ that could be detected by 23Na-MRI.

Methods

DOCA-pellets were implanted in 10 male FVB mice while a sham procedure was performed on 10 FVB mice. Subsequently, both groups received 1% NaCl water for 2 weeks. 23Na-MRI at 7Tesla was used to quantify Na+ in heart and skeletal muscle. Furthermore, electrolytes were determined chemically in both tissues. In a fraction of mice intracellular Na+ of the myocardium was measured by electron beam microscopy. Echocardiography was performed and blood pressure determined.

Results

Compared to control mice DOCA treated mice showed a significantly higher Na+ content in skeletal muscle (27.0 ± 5.7 vs. 46.6 ± 8.9 mmol/l, p<0.001) and in heart muscle (61.6 ± 9.1 vs. 73.7 ± 11.7, p<0.05, figure 1). The fraction of bound Na+ was increased in DOCA skeletal muscle (6.4 ± 0.8 vs. 13.0 ± 4.3 a.u., p<0.05) suggesting intracellular Na+ accumulation. Electron beam microscopy of heart muscle also detected a higher intracellular Na+ amount in DOCA animals compared to controls (0.12 ± 0.03 (n=4) vs. 0.29 ± 0.01 a.u. (n=3), p<0.001). Chemical electrolyte analysis confirmed Na+ accumulation in both tissues. A reduced ejection fraction (74 ± 4 vs. 46 ± 15%, p<0.05) and hypertension was found in DOCA animals.

Conclusion

Na+ accumulation occurs intracellularly in skeletal muscle and in heart muscle in vivo upon DOCA salt treatment indicating Na+ uptake rather than extracellular accumulation. Increased Na+ content of the myocardium might directly contribute to cardiac dysfunction.

Figure 1, representative MR images.

Funding

  • Government Support - Non-U.S.