The Ca2+ transient as a feedback sensor controlling cardiomyocyte ionic conductances in mouse populations
Colin M Rees,
Jun-Hai Yang,
Marc Santolini,
Aldons J Lusis,
James N Weiss,
Alain Karma
Affiliations
Colin M Rees
Physics Department, Northeastern University, Boston, United states; Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, United States
Jun-Hai Yang
Department of Medicine (Cardiology), Cardiovascular Research Laboratory, David Geffen School of Medicine, University of California, Los Angeles, United states; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, United States
Physics Department, Northeastern University, Boston, United states; Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, United States
Aldons J Lusis
Department of Medicine (Cardiology), Cardiovascular Research Laboratory, David Geffen School of Medicine, University of California, Los Angeles, United states; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, United States; Department of Microbiology, David Geffen School of Medicine, University of California, Los Angeles, United States; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, United States
James N Weiss
Department of Medicine (Cardiology), Cardiovascular Research Laboratory, David Geffen School of Medicine, University of California, Los Angeles, United states; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, United States
Physics Department, Northeastern University, Boston, United states; Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, United States
Conductances of ion channels and transporters controlling cardiac excitation may vary in a population of subjects with different cardiac gene expression patterns. However, the amount of variability and its origin are not quantitatively known. We propose a new conceptual approach to predict this variability that consists of finding combinations of conductances generating a normal intracellular Ca2+ transient without any constraint on the action potential. Furthermore, we validate experimentally its predictions using the Hybrid Mouse Diversity Panel, a model system of genetically diverse mouse strains that allows us to quantify inter-subject versus intra-subject variability. The method predicts that conductances of inward Ca2+ and outward K+ currents compensate each other to generate a normal Ca2+ transient in good quantitative agreement with current measurements in ventricular myocytes from hearts of different isogenic strains. Our results suggest that a feedback mechanism sensing the aggregate Ca2+ transient of the heart suffices to regulate ionic conductances.
