How cells outside the heart can affect the heart beat: The role of pulmonary vein sleeve cells for the development of atrial fibrillation

Rietdorf, Katja; Masoud, Said; McDonald, Fraser and Bootman, Martin (2016). How cells outside the heart can affect the heart beat: The role of pulmonary vein sleeve cells for the development of atrial fibrillation. In: Evolution brings Ca2+ and ATP together to control life and death, 16-17 Mar 2016, Kavli Royal Society Centre, Chicheley Hall, Newport Pagnell.

Abstract

Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia. A main cause of AF is cardiomyocyte-like cells found in pulmonary veins, called pulmonary vein sleeve cells (PVCs). These cells form a ~2 cm long sheath around the pulmonary vein of mammals. PVCs show spontaneous electrical and calcium signals for reasons that are unknown. The electrical signals arising the in the pulmonary veins propagate into the atria to cause AF. Ablation of the electrical connection between the pulmonary veins and the left atrium is the major surgical treatment for AF. Since the incidence of AF increases with age, we investigated how ageing alters calcium signalling and ultrastructure within PVCs.

PVCs from 3 month-old mice showed fewer spontaneous calcium signals, a shorter calcium transient duration and were more likely to follow electrical pacing than those from 24 month-old mice. In an EM study, we found an increased number and size of mitochondria, and an increase in the appearance of lipofuscin in PVCs from aged mice. Our data indicate that PVCs from aged mice showed more pro-arrhythmic calcium signals and marked ultrastructural changes. It is likely that changes in PVC ion homeostasis and cell structure contribute to the genesis AF.

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