Dynamics of calcium sparks and calcium leak in the heart

Biophys J. 2011 Sep 21;101(6):1287-96. doi: 10.1016/j.bpj.2011.07.021. Epub 2011 Sep 20.


We present what we believe to be a new mathematical model of Ca(2+) leak from the sarcoplasmic reticulum (SR) in the heart. To our knowledge, it is the first to incorporate a realistic number of Ca(2+)-release units, each containing a cluster of stochastically gating Ca(2+) channels (RyRs), whose biophysical properties (e.g., Ca(2+) sensitivity and allosteric interactions) are informed by the latest molecular investigations. This realistic model allows for the detailed characterization of RyR Ca(2+)-release properties, and shows how this balances reuptake by the SR Ca(2+) pump. Simulations reveal that SR Ca(2+) leak consists of brief but frequent single RyR openings (~3000 cell(-1) s(-1)) that are likely to be experimentally undetectable, and are, therefore, "invisible". We also observe that these single RyR openings can recruit additional RyRs to open, due to elevated local (Ca(2+)), and occasionally lead to the generation of Ca(2+) sparks (~130 cell(-1) s(-1)). Furthermore, this physiological formulation of "invisible" leak allows for the removal of the ad hoc, non-RyR mediated Ca(2+) leak terms present in prior models. Finally, our model shows how Ca(2+) sparks can be robustly triggered and terminated under both normal and pathological conditions. Together, these discoveries profoundly influence how we interpret and understand diverse experimental and clinical results from both normal and diseased hearts.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Allosteric Regulation
  • Calcium / metabolism*
  • Calcium Signaling*
  • Heart Diseases / metabolism
  • Heart Diseases / pathology
  • Models, Biological*
  • Myocytes, Cardiac / cytology*
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • Permeability
  • Ryanodine Receptor Calcium Release Channel / metabolism
  • Sarcoplasmic Reticulum / metabolism


  • Ryanodine Receptor Calcium Release Channel
  • Calcium