| Objectives: To investigate the effects of atrial fibrillation (AF) on autonomic nerve system in left atrial myocard of canines with vagally-mediated paroxysmal atrial fibrillation, and the effects of fastigial nucleus electrostimulation (FNS) on neurovegetative restitution relating to atrial fibrillation.Methods:Models of vagally-mediated paroxysmal atrial fibrillation were built, including AF group(n=5), FNS group(n=5), and 4 canines by sham operation as Sham group. Change of myocardial structure, density of positive AchE nerve fibers, expression of CHRM2 mRNA and ADRβ1 mRNA and level of AngⅡwere observation after obtaining myocard of left atria.Results: (1) In AF group, species of ultrastructural damage were observed in myocard under electron microscope. Densities of positive AchE nerve fibers (4.23±0.21)% compared with those of Sham group were increased in myocard of left atria(P<0.05). Expression of CHRM2 mRNA (0.51±0.01) and ADRβ1 mRNA (0.43±0.03) were downregulated (P<0.05), and level of AngⅡ(223.44±7.01 pg/ml) was increased( P<0.05 ) . (2) Compared with those of AF group, species of ultrastructural damage in myocard were suppressed by FNS under electron microscope, and expressions of CHRM2 mRNA (0.54±0.01) and ADRβ1 mRNA (0.57±0.04) in FNS group were upregulated(P<0.05), though lower than those of Sham group(P<0.05). Meanwhile, densities of positive AchE nerve fibers (3.75±0.14)% were decreased(P<0.05) by FNS , though more than those of Sham group(P<0.05). Level of AngⅡ(203.24±6.04 pg/ml) was reduced(P<0.05) by FNS, and had nosignificant diversity compared with those of Sham group(P>0.05). Conclusions: 1. Vagally-mediated paroxysmal atrial fibrillation led to neurovegetative restitution in myocard of left atria. 2. Fastigial nucleus stimulation can improve neurovegetative restitution.
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