Liu Ping, Xiang Ji-zhou, Zhao Lei, Yang Lei, Hu Ben-rong, Fu Qin
Department of Pharmacology, Tongji Hospital Huazhong University of Science and Technology, Wuhan 430030, China.
Acta Pharmacol Sin. 2008 Jun;29(6):661-9. doi: 10.1111/j.1745-7254.2008.00794.x.
To observe the effect of beta2-adrenergic agonist clenbuterol on ischemia/reperfusion (I/R) injury in isolated rat hearts and hydrogen peroxide (H2O2)-induced cardiomyocyte apoptosis.
Isolated rat hearts were subjected to 30 min global ischemia and 60 min reperfusion on a Langendorff apparatus. Cardiac function was evaluated by heart rate, left ventricular end-diastolic pressure (LVEDP), left ventricular systolic pressure, maximal rise rate of left ventricular pressure [+dp/dt(max)], and the coronary effluent (CF). Lactate dehydrogenase (LDH) in the coronary effluent, malondialdehyde (MDA), superoxide dismutase (SOD), and Ca2+-ATPase activity in the cardiac tissue were measured using commercial kits. The apoptotic cardiomyocyte was detected by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling (TUNEL) assay. Bax/Bcl-2 mRNA levels and the expression of caspase-3 were detected by RT-PCR and immunoblotting, respectively. Cultured newborn rat cardiomyocytes were preincubated with clenbuterol, and oxidative stress injury was induced by H2O2. Cell viability and cardiomyocyte apoptosis were evaluated by flow cytometry (FCM).
In the isolated rat hearts after I/R injury, clenbuterol significantly improved diastolic function (LVEDP and CF) and Ca2+-ATPase activity. Treatment with clenbuterol increased SOD activity and decreased the MDA level and LDH release compared with the I/R group (P<0.05). Moreover, clenbuterol decreased apoptosis, which was associated with a reduction in TUNEL-positive cells, Bax/Bcl-2 mRNA, and caspase-3 expression. In H2O2-induced cardiomyocyte injury, clenbuterol increased cell viability and attenuated cardiomyocyte apoptosis. Pretreatment with ICI118551 (selective beta2-adrenergic antagonist) decreased these effects compared with the clenbuterol-treated group (P<0.05).
Clenbuterol ameliorated ventricular diastolic function by enhancing Ca2+-ATPase activity and reduced oxidative stress and cardiac myocyte apoptosis in an experimental rat model of myocardium I/R. It decreased cardiomyocyte apoptosis induced by H2O2 in vitro. It plays a key role in the cardiac protection against myocardium I/R injury.
观察β2-肾上腺素能激动剂克伦特罗对离体大鼠心脏缺血/再灌注（I/R）损伤及过氧化氢（H2O2）诱导的心肌细胞凋亡的影响。
在Langendorff装置上对离体大鼠心脏进行30分钟全心缺血和60分钟再灌注。通过心率、左心室舒张末压（LVEDP）、左心室收缩压、左心室压力最大上升速率[+dp/dt(max)]和冠脉流出液（CF）评估心脏功能。使用商用试剂盒检测冠脉流出液中的乳酸脱氢酶（LDH）、心脏组织中的丙二醛（MDA）、超氧化物歧化酶（SOD）和Ca2+-ATP酶活性。通过末端脱氧核苷酸转移酶介导的地高辛-dUTP缺口末端标记（TUNEL）法检测凋亡心肌细胞。分别通过逆转录聚合酶链反应（RT-PCR）和免疫印迹法检测Bax/Bcl-2 mRNA水平和半胱天冬酶-3的表达。将培养的新生大鼠心肌细胞用克伦特罗预孵育，并用H2O2诱导氧化应激损伤。通过流式细胞术（FCM）评估细胞活力和心肌细胞凋亡。
在I/R损伤后的离体大鼠心脏中，克伦特罗显著改善了舒张功能（LVEDP和CF）以及Ca2+-ATP酶活性。与I/R组相比，克伦特罗治疗增加了SOD活性，降低了MDA水平和LDH释放（P<0.05）。此外，克伦特罗减少了凋亡，这与TUNEL阳性细胞、Bax/Bcl-2 mRNA和半胱天冬酶-3表达的减少有关。在H2O2诱导的心肌细胞损伤中，克伦特罗增加了细胞活力并减轻了心肌细胞凋亡。与克伦特罗治疗组相比，用ICI118551（选择性β2-肾上腺素能拮抗剂）预处理降低了这些作用（P<0.05）。
在实验性大鼠心肌I/R模型中，克伦特罗通过增强Ca2+-ATP酶活性改善心室舒张功能，减轻氧化应激和心肌细胞凋亡。它在体外减少了H2O2诱导的心肌细胞凋亡。它在心脏保护免受心肌I/R损伤中起关键作用。
