Sci. Signal., 29 January 2013
Setting the BeatA heartbeat requires the spontaneous firing of sinoatrial node cells followed by the contraction of ventricular myocytes. Sirenko et al. analyzed why sinoatrial node cells, rather than ventricular myocytes, are the pacemakers in the heart. Rhythmic spontaneous firing requires the spontaneous release of Ca2+ through ryanodine receptors from the sarcoplasmic reticulum, and sinoatrial node cells released more Ca2+ through ryanodine receptors in a rhythmic manner compared to ventricular myocytes, which released Ca2+ in a more random manner. The abundance and phosphorylation status of various proteins involved in Ca2+ cycling by the sarcoplasmic reticulum differed between sinoatrial node cells and ventricular myocytes, and these differences would be expected to contribute to the ability of sinoatrial node cells to release large amounts of Ca2+ from the sarcoplasmic reticulum in a rhythmic fashion. These insights may help in the design of gene- or cell-based biological pacemakers that could be used instead of electronic devices in individuals with abnormal heart rates caused by sinoatrial node dysfunctions.
Citation: S. Sirenko, D. Yang, Y. Li, A. E. Lyashkov, Y. O. Lukyanenko, E. G. Lakatta, T. M. Vinogradova, Ca2+-Dependent Phosphorylation of Ca2+ Cycling Proteins Generates Robust Rhythmic Local Ca2+ Releases in Cardiac Pacemaker Cells. Sci. Signal. 6, ra6 (2013).