Conduction of excitation in the rat atria and pulmonary veins under normal condition and after octanol applicationстатьяТезисы
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Аннотация:OBJECTIVE. Much attention is paid to the pulmonary veins (PVs) myocardium as a region responsible for atrial fibrillation triggering. Arrhythmogenic properties of PVs are partially associated with abnormal propagation of excitation wave. Decreased density and conductance of gap junction (GJ) were demonstrated in PVs in several studies. Functional role of altered GJ in suppression of conduction velocity (CV), formation of conduction blocks and PVs arrhythmogenity in is not completely clear. The aim of this study is to investigate conduction of excitation in rat PVs myocardium in condition of gap junction uncoupling.
METHODS. Rats (male, 250-300 g) were anaesthetized (urethane, 1.5 g/kg i.v.), multicellular preparations of left atrium (LA) and PVs of left lung lobe were dissected. Tyrode superfused LA and PVs preparations were treated with potential sensitive dye di-4-ANEPPS (5 µM) in presence of 2,3-butanedione monoxime (1 g/l) for excitation mapping. Optical signals were captured with use of CCD camera (WuTech Instruments). CV estimation and isochronic maps reconstruction were performed with use of Cardioplex software (RedShirtImaging). Conduction of excitation in LA and PVs was estimated both in normal condition and after uncoupling agent octanol (1,6 mM, up to 30 min) administration.
RESULTS. Rat LA and PVs demonstrate similar CV (63,3±4,5 (n=6) and 61,5±4,2 (n=8) cm/c, respectively). Octanol significantly suppress CV both in rat LA and PVs, but decreasing of CV in pulmonary veins after 6 min of octanol application was less prominent than in LA (40,8±4,7 and 28,4±2,9 cm/c, respectively, p(U)<0.05). Octanol was unable to induce single local conduction blocks in rat LA or PVs preparations. Prolonged administration of uncoupling agent finally leads to total suppression of LA and PVs conduction and excitability. Duration of period of excitability preserving during octanol perfusion was similar in LA and PVs (12,7±3,8 and 11,3±3,4 min, respectively).
CONCLUSIONS. Rat PVs probably less affected to octanol induced GJ uncoupling than atrial myocardium. Role of GJ uncoupling or intrinsic altered GJ in PVs conduction disturbances, particularly in rat, remains discussable.