Heart Automaticity

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Matteo E Mangoni - One of the best experts on this subject based on the ideXlab platform.

Angelo G Torrente - One of the best experts on this subject based on the ideXlab platform.

Pietro Mesirca - One of the best experts on this subject based on the ideXlab platform.

Isabelle Bidaud - One of the best experts on this subject based on the ideXlab platform.

Joel Nargeot - One of the best experts on this subject based on the ideXlab platform.

  • Heart Automaticity in mice lacking l type cav1 3 and t type cav3 1 ca2 channels insights into the cardiac pacemaker mechanism
    Archives of Cardiovascular Diseases Supplements, 2018
    Co-Authors: M Baudot, Joel Nargeot, Angelo G Torrente, Pietro Mesirca, Isabelle Bidaud, L Fossier, L Talssi, Heesup Shin, Joerg Striessnig, S Barrerelemaire
    Abstract:

    Introduction Sino-atrial node (SAN) pacemaker activity is generated by ion channels of the plasma membrane, such as hyperpolarization-activated “funny” f-(HCN), Ca2+ channels and ryanodine receptor (RyR) – dependent Ca2+ release from the sarcoplasmic reticulum (SR). It is currently disputed whether Ca2+ release from RyRs could sustain viable pacemaker activity provided preserved SR Ca2+ content. While working myocytes express L-type Cav1.2 channels to maintain SR Ca2+ content, SAN cells express also L-type Cav1.3 and T-type Cav3.1 channels to generate pacemaking. Objectives We used mutant mice carrying concomitant ablation of Cav1.3 and Cav3.1 (Cav1.3−/−/Cav3.1−/−) to study the importance of these channels in Automaticity. We also investigated the role of f-HCN channels and RyR-dependent Ca2+ release in residual pacemaker activity of mutant mice. Methods We employed in vivo telemetric recordings of Heart rate (HR) in Cav1.3−/−, Cav3.1−/− and Cav1.3−/−/Cav3.1−/− mice. We studied the consequences of pharmacologic inhibition of f-HCN and TTX-sensitive Na+ channels in mutant mice using Langendorff perfused Hearts or optical mapping (OM) of the pacemaker impulse in intact SAN preparations (SANs). Results Cav ablation reduced HR in mice: Cav3.1−/− (−7.6%, n = 11), Cav1.3−/− (−24.4%, n = 8), Cav1.3−/−/Cav3.1−/− (−35%, n = 11). In OM experiments on SANs, concomitant inhibition of f-HCN and Nav1.1 channels slowed pacemaking in wild-type (−48%, n = 7) and Cav3.1−/− (−37%, n = 7), while arresting Automaticity in 4/6 of Cav1.3−/−, 3/6 of Cav1.3−/−/Cav3.1−/−. When present, residual pacemaking was reduced by 82%. Similar results were obtained using isolated Cav1.3−/−/Cav3.1−/− pacemaker cells were Automaticity arrested in 5/9 cells tested, or was reduced by 80% in 4/9 cells. Conclusion Heart Automaticity is primarily generated by Cav1.3 and f-HCN channels. RyR-dependent Ca2+ release cannot sustain Automaticity following concomitant targeting of Cav1.3 and f-HCN channels.

  • genesis and regulation of the Heart Automaticity
    Physical Review, 2008
    Co-Authors: Matteo E Mangoni, Joel Nargeot
    Abstract:

    The Heart Automaticity is a fundamental physiological function in higher organisms. The spontaneous activity is initiated by specialized populations of cardiac cells generating periodical electrica...