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背景:增龄是心房颤动发生的独立危险因素,心房肌细胞电生理特性的变化是触发和维持心房颤动的重要因素。目的:观察不同年龄犬左心房肌细胞动作电位和L型钙通道的改变。方法:实验纳入7只成年犬和10只老年犬,用Ⅱ型胶原酶分离成年犬和老年犬的左心房肌细胞,用全细胞膜片钳方法记录成年犬和老年犬左心房肌细胞动作电位和L型钙通道电流;采用实时荧光定量PCR和Western blot检测左心房肌L型钙通道α1c亚基mRNA和蛋白的表达。结果与结论:与成年犬相比,老年犬左心房肌细胞动作电位平台期的幅度明显降低(P<0.05),动作电位时程明显延长(P<0.05),而最大舒张电位和动作电位幅度在老年犬和成年犬间差异无显著性意义(P>0.05);同时老年犬左心房肌细胞的L型钙通道电流密度较成年犬明显降低(P<0.05),而L型钙通道电流动力学参数在成年犬和老年犬间差异无显著性意义(P>0.05);此外,与成年犬相比,老年犬左心房肌L型钙通道α1c亚基mRNA和蛋白的表达明显降低(P<0.05)。由此认为,左心房肌细胞电生理学特性存在增龄性改变。
BACKGROUND: Aging is an independent risk factor for atrial fibrillation. Changes in the electrophysiological properties of atrial myocytes are important factors that trigger and maintain atrial fibrillation. Objective: To observe the changes of action potentials and L-type calcium channels in left atrial myocytes of dogs at different ages. Methods: Seven adult dogs and 10 elderly dogs were included in the experiment. Type Ⅱ collagenase was used to separate left atrial myocytes from adult dogs and aged dogs. Whole-cell patch-clamp method was used to record the action potentials of left atrial myocytes of adult dogs and aged dogs. L-type calcium channel current. The mRNA and protein expression of L-type calcium channel α1c subunit of left atrium were detected by real-time fluorescence quantitative PCR and Western blot. RESULTS AND CONCLUSION: Compared with adult dogs, the amplitude of action potential of left atrial myocytes in elderly dogs was significantly decreased (P <0.05) and the duration of action potential was significantly longer (P <0.05), while the maximal diastolic and action potential amplitudes There was no significant difference between aged dogs and adult dogs (P> 0.05). At the same time, the current density of L-type calcium channel in left atrial myocytes of elderly dogs was significantly lower than that of adult dogs (P <0.05) There were no significant differences in learning parameters between adult dogs and aged dogs (P> 0.05). In addition, compared with adult dogs, the expressions of L-type calcium channel α1c subunit mRNA and protein in left atrium of elderly dogs were significantly decreased (P < 0.05). Therefore, there is an age-related change in the electrophysiological characteristics of left atrial myocytes.