| Objective:To obseve the effect and mechanisms of shensong yangxin(SSYX)capsule on the paroxymal atrial fibrillation.Methods:Eighteen mongrel dogs were randomly divided into control group(n = 6),pacing group(n = 6),and pacing + SSYX group(n = 6).The control group was implanted with pacemakers without pacing;the pacing group was implanted with pacemakers with long-term intermittent atrial pacing;the pacing + SSYX group underwent long-term intermittent atrial pacing and SSYX oral administration.A 2ml venous blood was collected and the heart rate variations of each canine was recorded in the baseline and at the end of the study to test the level of angiotensin Ⅱ(AngⅡ),aldosterone(ALD),tumor necrosis factor-alpha(TNF-α),interleukin-6(IL-6)and acetylcholine(ACH).The indexes of cardiac electrophysiology and atrial fibrillation were tested,and the distribution of TH(Tyrosine hydroxylase)and ChAT(Choline acetyltransferase)were detected by immunohistochemistry in the left and right atria after the experiment.The TNF-α,IL-6 and α7nAChR levels were examed by immunohistochemistry in the left and right atrial tissues.Results1.There were no significant differences in the parameters of HRV between baseline and after 8 weeks in the control group.After 8 weeks,the LF and LF/HF showed an increasing trend in the pacing + SSYX group,but this did not attain statistical significance.Compared to the parameters at baseline,LF and LF/HF increased and HF decreased significantly after 8 weeks in the pacing group(LF:P = 0.003;LF/HF:,P=0.001;HF:P = 0.046).LF and LF/HF were lower,and HF was higher after 8 weeks in the control and pacing + SSYX groups than those in the pacing group(all P<0.05)2.The AERPs were shorter in the pacing group than in the control and pacing + SSYX groups after 8 weeks(P<0.05 for all),and the dAERP was higher in the pacing group than in the control group(P<0.001)and pacing + SSYX group(P<0.001).Compared with the control,the pacing and pacing + SSYX groups had significantly more episodes of AF(P<0.01,P<0.001)respectively and longer durations of AF(P<0.001,P<0.001 respectively,during programmed stimulation after long-term intermittent atrial pacing.However,compared with the pacing group,the pacing +SSYX dogs had fewer episodes of AF(P = 0.033)and shorter durations of AF(P =0.006).The densities of TH positive nerves within the RA were significantly higher in the pacing group and pacing + SSYX group dogs than in the control dogs(P<0.001,P<0.001)respectively.However,the densities of TH positive nerves within the RA were significantly higher in the pacing group than in the pacing + SSYX group(P=0.015).There were no significant differences between ChAT positive nerve densities in control and pacing dogs(P = 0.363).Compared to the pacing group,there was an increasing in ChAT positive nerve densities of the pacing +SSYX group dogs.However,this result was not statistically significant(P=0.079).The densities of TH positive and ChAT positive nerves in the LA are similar to that in the RA。3.There were no significant differences in the plasma AngⅡ and ALD at baseline among the three experimental groups.Compared with the control group,the plasma AngⅡ and ALD concentrations were higher in the pacing and the pacing +SSYX dogs(all P<0.001)after 8 weeks.However,compared with that in the pacing group,the plasma AngⅡ and ALD concentrations were lower in the pacing+ SSYX dogs.(P<0.05 and P<0.05)respectively.4.There were no significant differences in the plasma TNF-α,IL-6,and ACH at baseline among the three experimental groups.After 8 weeks,the plasma TNF-α and IL-6 concentrations were all significantly increased compared with the baseline in the pacing group,respectively.However,the levels of ACH was significantly decreased compared with the baseline(P<0.001).In the pacing +SSYX group,the plasma TNF-α and IL-6 concentrations all significantly increased compared with the baseline(P<0.001;P = 0.001),respectively after 8 weeks.The levels of Ach was significantly decreased compared with the baseline(P=0.001).Compared with the control,the plasma TNF-α and IL-6 concentrations were higher in the pacing and the pacing + SSYX dogs(all P<0.001)after 8 weeks.However,compared with that in the pacing group,the plasma TNF-α and IL-6 concentrations were lower in the pacing + SSYX dogs(P= 0.001 and P<0.001,respectively),and the levels of Ach were higher in the pacing + SSYX dogs(P<0.001)5.The level of a7nAChR protein was reduced in RA and LA of the pacing group dogs compared with the control and the pacing + SSYX groups dogs(P<0.001),while TNF-α and IL-6 in LA and RA tissues were significantly higher in the pacing group than in the control and the pacing + SSYX group(P<0.001).Compared with the control group,the levels of TNF-α and IL-6 were higher(P<0.001),and the levels of a7nAChR were lower in the LA and RA tissues in the pacing + SSYX group(P<0.001).Conclusions:SSYX can inhibit the induction of atrial fibrillation after intermittent long-term right atrial pacing,and its mechanism is related to the effects of cardiac electrical remodeling,autonomic nervous balance,RAAS system activity and cholinergic anti-inflammatory pathway... |
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