Display options
Cite
Torres CA, Varian KD, Janssen PM. Variability in interbeat duration influences myocardial contractility in rat cardiac trabeculae. Open Cardiovasc Med J. 2008;2:100-4doi: 10.2174/1874192400802010100.
Torres, C. A., Varian, K. D., & Janssen, P. M. (2008). Variability in interbeat duration influences myocardial contractility in rat cardiac trabeculae. The open cardiovascular medicine journal, 2100-4. https://doi.org/10.2174/1874192400802010100
Torres, Carlos A A, et al. "Variability in interbeat duration influences myocardial contractility in rat cardiac trabeculae." The open cardiovascular medicine journal vol. 2 (2008): 100-4. doi: https://doi.org/10.2174/1874192400802010100
Torres CA, Varian KD, Janssen PM. Variability in interbeat duration influences myocardial contractility in rat cardiac trabeculae. Open Cardiovasc Med J. 2008;2:100-4. doi: 10.2174/1874192400802010100. Epub 2008 Nov 21. PMID: 19440237; PMCID: PMC2627530.
Copy Download .nbib Format: NLM
Share it on

Open Cardiovasc Med J. 2008;2:100-4. doi: 10.2174/1874192400802010100. Epub 2008 Nov 21.

Variability in interbeat duration influences myocardial contractility in rat cardiac trabeculae.

The open cardiovascular medicine journal

Carlos A A Torres, Kenneth D Varian, Paul M L Janssen

Affiliations

  1. Department of Physiology and Cell Biology, and Department of Emergency Medicine, 304 Hamilton Hall, 1645 Neil Avenue, The Ohio State University, Columbus, OH, USA.

PMID: 19440237 PMCID: PMC2627530 DOI: 10.2174/1874192400802010100

Abstract

There is an intense search for positive inotropic strategies. It is well known that the interbeat duration is a critical determinant of cardiac contractility. Generally, when frequency increases, so does contractile strength. We hypothesize that the beat-to-beat variability at a given heart rate also modulates cardiac contractility. To test this hypothesis, thin, uniform rat cardiac trabeculae were isolated from the right ventricle and stimulated to isometrically contract, alternating between fixed steady state versus variable inter-beat intervals (same total number of beats in each period). Trabeculae were stimulated at 4 Hz with interbeat variation between 20 and 120% (n=17). In a second series of experiments trabeculae were stimulated at 3 different physiologic frequencies with a 40% interbeat variation. Fixed rate response was measured before and after each variable period and average force was calculated. In order to investigate the mechanism underlying the changes in contractility we used iontophoretically loaded bis-fura-2 salt to monitor intracellular calcium transients. We observed no significant change in force at 4 Hz (n=17), and 6 Hz (n=6) between fixed and variable pacing but observed a significant, 10% increase in contractile strength at 8 Hz (from 15.1 to 16.5 mN/mm(2), p<0.05, n=6). Our results show that under certain conditions, by simply introducing variation in the beat-to-beat duration without affecting the number of beats per minute, a positive inotropic effect with corresponding changes in the calcium transients can be generated.

References

  1. Am J Cardiol. 1988 Jun 1;61(15):1292-9 - PubMed
  2. Pflugers Arch. 2006 Feb;451(5):625-30 - PubMed
  3. Am J Physiol. 1992 Jul;263(1 Pt 2):H293-306 - PubMed
  4. J Physiol. 2002 Nov 1;544(3):817-30 - PubMed
  5. J Clin Invest. 1996 Aug 1;98(3):764-76 - PubMed
  6. Cardiovasc Res. 1995 Aug;30(2):212-21 - PubMed
  7. Braz J Med Biol Res. 2004 Dec;37(12):1895-902 - PubMed
  8. Adv Exp Med Biol. 1998;453:441-50; discussion 451 - PubMed
  9. Am Heart J. 1995 Apr;129(4):748-53 - PubMed
  10. Am J Physiol. 1994 Mar;266(3 Pt 2):H1202-13 - PubMed
  11. J Mol Cell Cardiol. 1995 Jan;27(1):523-30 - PubMed
  12. Circulation. 1993 Oct;88(4 Pt 1):1682-90 - PubMed
  13. J Am Coll Cardiol. 1997 Oct;30(4):1039-45 - PubMed
  14. Am J Cardiol. 1996 Dec 15;78(12):1433-6 - PubMed
  15. Am J Physiol. 1999 Jan;276(1):H9-H18 - PubMed
  16. J Mol Cell Cardiol. 1999 Aug;31(8):1419-27 - PubMed
  17. Am J Physiol Heart Circ Physiol. 2002 Feb;282(2):H499-507 - PubMed
  18. Eur Heart J. 1994 Feb;15(2):164-70 - PubMed
  19. Eur Heart J. 2005 Apr;26(7):705-11 - PubMed
  20. Methods Inf Med. 2007;46(2):191-5 - PubMed
  21. J Mol Cell Cardiol. 2002 Oct;34(10):1367-76 - PubMed
  22. Circ Res. 1989 Nov;65(5):1441-9 - PubMed

Publication Types