RESUMO
Objective: To observe the impact of high thoracic epidural blockade (HTEB) on atrial autonomic nerve remodeling in dogs with atrial ifbrillation (AF) induced by long-term rapid right atrial appendage pacing and to explore the effect of nerve growth factor (NGF) on atrial autonomic nerve remodeling. Methods: AF model was established by consistent rapid atrial pacing for 6 weeks. 18 experimental dogs were randomly divided into 3 groups: Sham group, the dogs had no pacing while received normal saline injection; Control group, the dogs had pacing and normal saline injection; HTEB group, the dogs had pacing and 0.5% lidocaine injection for HTEB.n=6 in each group. Atrial myocardium collagen volume fraction (CVF) was examined by Masson staining; sprouting of NGF related protein 43 (GAP43) and tyrosine hydroxylase (TH) were assessed by immunohistochemistry; protein expressions of NGF, GAP43 and TH were measured by Western blot analysis. Results: Compared with Sham group, HTEB group showed decreased CVF and sprouting of GAP43, TH,P Conclusion: Long-term rapid atrial pacing induced AF dog had inhomogeneous sprouting of atrial myocardial nerve which may cause autonomic nerve remodeling; NGF played the important role in such process. HTEB could effectively inhibit NGF up-regulation and suppress the autonomic nerve remodeling in experimental dogs.
RESUMO
Aim To investigate the preventive effect of Guizhi decoction on cardiac sympathetic sprouting induced by 4-Methylcatechol (4-MC) . Methods The rat models of cardiac sympathetic sprouting were in-duced by 10 mg · L-1 4-MC ( 10μg · kg-1 body weight, i. p. ) . Guizhi decoctions ( with different pro-portion between Ramulus Cinnamomi and Radix Paeon-iae Alba, 1 : 1, 1 : 2 and 2 : 1) and metoprolol were administered to the rats. Heart rate and electrocardio-gram ( ECG ) were observed, the content of norepi-nephrine (NE), growth associated protein (GAP-43), tyrosine hydroxylase ( TH ) and acetylcholine transfer-ase enzyme ( CHAT) in myocardial homogenate of left ventricular and right atrial were determined by ELISA method, and immunofluorescence assay was used to observe cardiac nerve sprouting and sympathetic distri-bution. Results 4-MC caused cardiac sympathetic sprouting and parasympathetic was not influenced. Heart rate of the model group was improved significant-ly and higher than that of the other groups . Compared with the model group, the content of NE, GAP-43 and TH in left ventricle and right atrium of the metoprolol group and Guizhi decoction group were decreased( P<0.05 ) , and the immunofluorescence result showed that the distribution of TH positive nerve was reduced sig-nificantly(P<0.05). It was demonstrated that Guizhi decoction of the proportion between Ramulus Cinnamo-mi and Radix Paeoniae Alba 1 : 1 and 1 : 2 had the best efficacy, which was similar to the efficacy of meto-prolol. Conclusion Guizhi decoction ( with the pro-portion between Ramulus Cinnamomi and Radix Paeon-iae Alba 1 : 1 and 1 : 2 ) effectively inhibits the cardi-ac sympathetic sprouting induced by 4-MC.