犬心房颤动模型缝隙连接蛋白40、45与心肌纤维化的相关性  

Association between myocardial connexin 40 and 45 expression and myocardial fibrosis in the rapid atrial pacing canine model

作　　者：邢晓倩 徐健[1] 苏浩[1] 芦监伟[1] 

机构地区：[1]安徽省立医院心内科,合肥230001 [2]芜湖市第二人民医院心内科

出　　处：《中华心血管病杂志》2011年第2期176-180,共5页Chinese Journal of Cardiology

基　　金：安徽省自然科学基金（090413128）

摘　　要：目的 心房颤动（房颤）的发生及维持机制与心房结构重构和电重构有关。缝隙连接蛋白（connexin，Cx）是心肌闰盘的重要组成结构。一旦Cx出现重构，可影响心肌细胞电传导的极性，出现传导阻滞或折返，引发心律失常。实验通过快速心房起搏建立房颤模型，观察其对心房Cx40和Cx45及心房心肌纤维化的影响，并对两者相关性进行研究。方法16只健康杂种犬随机分为模型组和对照组，2组犬均在x线下置人心房“J”型电极于右心耳，模型组予以400次／min快速起搏，而对照组维持窦性心律。连续起搏10周，分别在2、4、6、8周检测肢导联心电图。对于10周后未出现房颤的犬予以房颤诱发。实验结束后，取左心房组织制备心肌组织切片。Masson染色观察心房心肌胶原改变，电镜观察心房心肌超微结构及闰盘改变，放射免疫法测定血清中Ⅲ型前胶原氨基端肽和Ⅳ型胶原，免疫组化法检测Cx40及Cx45的表达。结果模型组在快速起搏10周后均未出现自发性房颤，但其中有2只犬分别出现心房扑动和房性早搏，模型组和对照组予以Burst刺激后，模型组房颤诱发率可达66．7％，而对照组均正常。与对照组相比，模型组心房心肌胶原容积分数（collagen volume fraction，CVF）增加（P〈0．05），尤以心内膜和心房肌细胞问质纤维化明显。电镜下，模型组心房肌细胞超微结构可见肌纤维紊乱、断裂，胶原纤维增生，闰盘结构扭曲、扩张，部分闰盘缝隙消失。模型组血清中Ⅲ型前胶原氨基端肽和Ⅳ型胶原水平较对照组显著增高（P〈0．05）；模型组心房心肌Cx40表达较对照组增加（P〈0．05），而Cx45蛋白改变二组差异无统计学意义（P〉0．05）。将心房心肌组织CVF与Cx40行相关性分析，结果显示CVF与Cx40呈正相关（r=0．671）。结论犬心房快速起搏能诱导左心房组织心肌纤维化和Cx40Objective Electrical and structural remodeling are of importance for the occurrence and maintenance of atrial fibrillation. We observed association between atrial connexin protein expression and fibrosis in a canine model of prolonged rapid atrial pacing. Methods ＂J＂-type electrodes were placed in the right atrial appendage under the guidance of X-ray in 16 dogs, Animals in model group （ n = 8 ） received fast pacing （400 beats/rain ） for 10 weeks while animals in control group （n = 8） maintained at sinus rhythm. Limb-lead ECGs were recorded at 2,4,6,8 weeks respectively. Burst stimulation was applied to induce atrial fibrillation in all animals after 10 weeks, animals were sacrificed thereafter and the left atrial tissues were taken for myocardial collagen measurement （ Masson staining） and myocardial ultrastructure examination and detection of protein expression of eonnexin （ Cx ） 40 and 45 （ immune staining ） . Procollagen type Ⅲ N-terminal peptide and type Ⅳ collagen in serum were also detected by radioimmunoassay. Results Two dogs died in model group due to atrial rupture induced cardiac tamponade or lung embali. Spontaneously atrial fibrillation was not observed in all animals, but two dogs developed atrial flutter and atrial premature beats. Atrial fibrillation was induced by burst stimulation in 4 out of 6 dogs in model group and in none of the dogs in control group. Atrial myocardial collagen volume fraction was significantly increased in model group compared with the control group （P 〈 0. 05 ）. Ultrastructure examination in atrial tissue evidenced disorder,fracture, collagen fiber proliferation, mitochondrial swelling, blurred eristae, and intercalated disc distortion, expansion, part of gap junction disappears in model group. The serum levels of procollagen type Ⅲ N-terminal peptide and type Ⅳ collagen in model group were significantly higher than in the control group （P 〈0. 05）. The protein expression of Cx40 in atrial myocardium in model group was signif

关 键 词：心房颤动 心脏起搏 人工 心肌 连接蛋白类 

分 类 号：R541.7[医药卫生—心血管疾病]