氧化应激对心房颤动犬心房病理组织学及超微结构改变的影响

目的 观察氧化应激对慢性心房快速起搏诱发心房颤动(房颤)犬心房肌钙激活蛋白酶Ⅰ表达及肌细胞超微结构改变的影响.方法 20只犬无菌条件下开胸手术,植入高频起搏器(400次/分),建立房颤犬模型,分为假手术组(不起搏),对照组和普罗布考组心房快速起搏6周.普罗布考组于起搏前1周服用普罗布考(100 mg/kg),至起搏6周结束.采用免疫组化方法和Western印迹法检测各组犬心房肌钙激活蛋白表达情况;分别于起搏前和起搏6周后,记录各组犬房颤诱发情况;比色法检测各组犬心房肌氧化应激相关指标.结果 对照组左、右心房肌肌溶解比率(53.6±11.8)%,(58.5±9.2)%]比假手术组(4.4±3.1)%,(4.1±2.9)%]显著增加(P＜0.01);对照组比假手术组心房肌细胞线粒体肿胀伴糖原沉积明显,心房肌钙激活蛋白酶Ⅰ表达显著上调(P＜0.01);普罗布考组左、右心房肌细胞病理组织学和超微结构改变比对照组明显减轻,肌溶解比率明显减少(12.3±3.2)%,(12.0±2.6)%,P＜0.01],钙激活蛋白酶Ⅰ表达显著下调(P＜0.01).普罗布考组心房肌MDA水平比对照组显著降低(P＜0.01),T-AOC和抗O2-水平明显增加(P＜0.01),房颤诱发率和平均持续时间显著减少(均P＜0.01).心房肌钙激活蛋白酶Ⅰ表达和MDA均与肌溶解程度呈显著正相关(r=0.958,r=0.939,P＜0.01).结论 普罗布考能够通过抑制氧化应激,抑制房颤犬心房肌肌溶解等病理组织学和超微结构变化,防止心房颤动犬心房重构,减少房颤发生.

Influence of oxidative stress on atrial myocardium pathohistological and ultrastructural changes in atrial fibrillation: experiment with dogs

OBJECTIVE: To evaluate the effects of oxidative stress on the protein expression of atrial calpain I and pathohistological and ultrastructural changes of atrial myocardium in atrial fibrillation (AF). METHODS: Twenty dogs were all implanted with pacemaker in a subcutaneous pocket and attached to a screw-in epicardial lead in right atrial appendage. They were randomly divided into 3 groups: sham-operation group (n = 6 without pacing), control group (n = 7 per minutes for 6 weeks), and probucol group (n = 7, pacing 1 week after recovery for 6 weeks, and administration of probucol 100 mg x kg(-1) x d(-1) 1 week before pacing till the end of pacing). One thin silicon plaque containing 4 pairs of electrodes were sutured to the right atrium. The dogs in control group, probucol group were paced at 400 beats per minutes for 6 weeks. Then the dogs were killed with their hearts taken out. The expression of atrial calpain I was measured by Western-blotting and immunohistochemistry. The pathohistological and ultrastructural changes in atrial tissue were tested by light and electron microscopy. The inducibility and duration of AF were measured in the control group and probucol group. The indexes of oxidative stress total anti-oxidation capability (T-AOC), malonyldiadehyde (MDA), and scavenging activities of superoxide anion (O2-) radical were measured by colorimetric method. RESULTS: The percentage of myolysis in the left and right atria of the control group were (53.6 +/- 11.8)% and. (58.5 +/- 9.2)% respectively, significantly higher than those of the sham operation group (4.4 +/- 3.1)% and (4.1 +/- 2.9)% respectively, both P < 0.01]. The percentage of myolysis in the left and right atria of the probucol group were (12.3 +/- 3.2)% and (12.0 +/- 2.6)% respectively, both significantly lower than those of the control group (both P < 0.01). The protein expression of calpain I of the control group was significantly higher than that of the sham-operation group, and the protein expression of calpain I of the probucol group was significantly lower than that of the control group. The AF inducibility rate after pacing of the probucol group was 60%, significantly lower than that of the control group (92.9%, P < 0.01). The average AF duration time after pacing of the probucol group was (601 +/- 328) s, significantly shorter than that of the control group (1458 +/- 498) s. The indexes of oxidative stress in probucol group were lower than the level in control group. The MDA levels of the probucol group was (3.08 +/- 0.20) mmol/mg protein, significantly lower than that of the control group (4.15 +/- 0.23) mmol/mg protein). The anti-O2- and T-AOC level of the probucol group were 279 +/- 20 U/g protein and 30.5 +/- 1.3 nmol/mg protein, both significantly higher than those of the control group (215 +/- 16 U/g protein and 25.6 +/- 1.5 nmol/mg protein respectively, both P < 0.01). There were more sarcomere vacuolization and dissolution in atrial myocytes in the control group than in the sham operation group. And the pathohistological and ultrastructrual changes of the probucol were lighter than those of the control group. CONCLUSION: Probucol prevents the pathohistological and ultrastructural changes in atrial myocardium by inhibiting calpain I expression, thus suppressing atrial structural remodeling, and preventing the induction and promotion of AF.