The susceptibility of the rat pulmonary and caval vein myocardium to the catecholamine‐induced ectopy changes oppositely in postnatal development

Abstract

The developmental changes of the caval (SVC) and pulmonary vein (PV) myocardium electrophysiology are traced throughout postnatal ontogenesis.r The myocardium in SVC as well as in PV demonstrate age-dependent differences in the ability to maintain resting membrane potential, to manifest automaticity in a form of ectopic action potentials in basal condition and in responses to the adrenergic stimulation.r Electrophysiological characteristics of two distinct types of thoracic vein myocardium change in an opposite manner during early postnatal ontogenesis with increased proarrhythmicity of pulmonary and decreased automaticity in caval veins.r Predisposition of PV cardiac tissue to proarrhythmycity develops during ontogenesis in time correlation with the establishment of sympathetic innervation of the tissue.r The electrophysiological properties of caval vein cardiac tissue shift from a pacemaker-like phenotype to atrial phenotype in accompaniment with sympathetic nerve growth and adrenergic receptor expression changes.

Automatic Activity Arising in Cardiac Muscle Sleeves of the Pulmonary Vein

“…Although this review focuses on the physiology of the PV myocardial sleeves, similar results have also been observed in the rat superior vena cava (SVC) and azygos vein [ 31 , 45 , 72 ], in which myocardial sleeves also extend and constitute a source of arrhythmia in humans [ 2 ]. The effects of age on the induction of CAA in the SVC and PV was also explored [ 31 ]. CAA occurred mainly in the SVC of young animals and its incidence decreased with age to become rare in adult animals.…”

“…In the mouse, catecholamine fibers were concentrated in the PV rather than in the LA appendage [ 30 ]. In the rat, the density of catecholamine fibers in the PV increased with post-natal age [ 31 ]. These data suggest that autonomic innervation might be an important actor in the regulation of PV excitability and in the genesis of abnormal automatism triggered in the PV, as depicted in the following sections.…”

“…Moreover, moderate stretch applied to the PV facilitated the development of arrythmogenic activity induced by a high concentration of adrenaline [ 69 ]. The predisposition of rat PV to show CAA evoked by NA has been found to develop with age and the post-natal development of the sympathetic innervation [ 31 ].…”