Electrical propagation in the various sites of the pulmonary veins of mammalianстатьяТезисы
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Аннотация:OBJECTIVES. Pulmonary veins (PVs) are characterized by unique properties – interposition of the two types of electrical excitable tissues: smooth and cardiac muscle layers. Some mammalians demonstrate tight interaction of the broad areas of extremely thin cardiac layer and smooth muscle in PVs “tree”. However, electrical contact and functional interaction between these tissues remains questionable. The aim of the present study is to investigate conduction of excitation in various sites of pulmonary veins tree and to determine possible influence of “smooth muscle factors” on the conduction.
METHODS. Multicellular preparations of left atrium (LA) or PVs of left lung lobe were dissected from rabbits (male, 2.6-3.2 kg, n=8), rats (male, 200-250 g, n=20) and guinea pigs (GP, male, 250-300 g, n=5). Preparations were perfused in standard conditions with Tirode solution.
Conduction of excitation was estimated with use of optical mapping technique (potential sensitive dye - di-4-ANEPPS, CCD camera - WuTech Instruments, software – RedShirtImaging). Conduction parameters were separately defined in LA, LA and PV junction region (PVJ), in PVs on the level of bifurcations (PVB), intrapulmonary region of PV (IP). Also, action potentials (APs) were recorded in all sites of preparations with applying of standard microelectrode technique.
RESULTS. Rat and GP demonstrates excitability and conduction of excitation in PVJ, PVB, IP (in rat) regions of PVs. Conduction velocity, anisotropy of conduction were approximately similar in all PV sites and similar to those of the LA. Rabbit characterized by only small PVJ zone, which conduct the excitation.
Removing of endothelium did not affect conduction or APs in any sites of rat PVs. Also, NO-donor application was unable to evoke significant conduction alteration. APs alteration in rat PVs sites, after NO-donor application, was indistinguishable from LA.
CONCLUSIONS. Thin layer of myocardium in rat and GP PVs tree, which is adjacent to smooth muscle, reveal conduction similar to LA. Probably, smooth muscle does not interact with or, at least, unable to significantly affect the bioelectrical activity of cardiac tissue in PVs.