Key result
Exercise training induces AV node dysfunction and PR prolongation via microRNA-mediated downregulation of pacemaking channels.
Why the study?
Atrioventricular block in athletes is typically attributed to high vagal tone, but whether electrical remodeling of the atrioventricular node is responsible remained unknown.
Does exercise training cause intrinsic electrical remodeling of the atrioventricular node leading to AV block in animal models?
Population
Sedentary and trained Standardbred racehorses, and sedentary and swim-trained mice
Comparison
Exercise training vs sedentary state
Design
Preclinical animal physiology and molecular study
Authors
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Supports intrinsic remodeling beyond vagal tone in exercised animals; leaves open human relevance and mechanisms.
Does exercise training cause intrinsic electrical remodeling of the atrioventricular node leading to AV block in animal models?
Exercise-induced atrioventricular block in athletes is likely driven by intrinsic electrical remodeling of the AV node via microRNA-mediated downregulation of key ion channels, challenging the traditional view that it is solely due to high vagal tone.
Mesirca et al. (2021) studied Atrioventricular block. Exercise training vs. Sedentary controls was evaluated on Atrioventricular node electrophysiology and ion channel expression. Exercise training induced atrioventricular node dysfunction and PR prolongation through microRNA-mediated transcriptional downregulation of key pacemaking ion channels (CaV1.2 and HCN4).
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