Rat pulmonary vein cardiomyocytes exhibit marked structural heterogeneity and significantly higher spontaneous calcium wave frequencies compared to left atrial cardiomyocytes (5.5 vs 0.8 waves/90 s).
Absolute Event Rate: 5.5% vs 0.8%
p-value: p=<0.05
Abstract Mechanisms underlying ectopic activity in the pulmonary vein (PV) which triggers paroxysmal atrial fibrillation are unknown. Although several studies have suggested that calcium signalling might be involved in these arrhythmias, little is known about calcium cycling in PV cardiomyocytes (CM). We found that individual PV CM showed a wide range of transverse tubular incidence and organization, going from their virtual absence, as described in atrial CM, to well transversally organised tubular systems, like in ventricular CM. These different types of CM were found in groups scattered throughout the tissue. The variability of the tubular system was associated with cell to cell heterogeneity of calcium channel (Ca v 1.2) localisation and, thereby, of Ca v 1.2-Ryanodine receptor coupling. This was responsible for multiple forms of PV CM calcium transient. Spontaneous calcium sparks and waves were not only more abundant in PV CM than in LA CM but also associated with a higher depolarising current. In conclusion, compared with either the atrium or the ventricle, PV myocardium presents marked structural and functional heterogeneity.
Pasqualin et al. (Tue,) conducted a other in Atrial Fibrillation (Arrhythmogenic mechanisms). Pulmonary vein cardiomyocytes vs. Left atrial and left ventricular cardiomyocytes was evaluated on Calcium wave frequency (waves/90 s) (p=<0.05). Rat pulmonary vein cardiomyocytes exhibit marked structural heterogeneity and significantly higher spontaneous calcium wave frequencies compared to left atrial cardiomyocytes (5.5 vs 0.8 waves/90 s).