Department of Internal Medicine, Cardiology Division (M-HH, YW, VN, SR, BFU, KF), University of Texas Medical Branch, Galveston, TX, USA.
Cardiovasc Drugs Ther. 2011 Jun;25(3):223-32. doi: 10.1007/s10557-011-6302-z.
The present study determined whether late-ischemia/early reperfusion therapy with the β(1)-adrenergic receptor (AR) blocker esmolol and phosphodiesterase III inhibitor milrinone reduced left ventricular (LV) myocardial infarct size (IS).
In an ischemia/reperfusion rat model (30-min ischemia/4-hr reperfusion), esmolol, milrinone or esmolol + milrinone were intravenous (IV) infused over 10 min (from the last 5 min of ischemia to the first 5 min of reperfusion). LV-IS were 48.9 ± 8.9%, 41.5 ± 5.4%, 25.8 ± 7.7% and 16.8 ± 7.3% for saline, esmolol, milrinone, and esmolol + milrinone, respectively (n = 12/group). Esmolol + milrinone further reduced LV-IS compared with esmolol or milrinone alone (p < 0.05). LV-IS-reduction induced by esmolol + milrinone was eliminated in the presence of protein kinase A-(PKA)-inhibitor (Rp-cAMPS) or Akt-inhibitor (AKT 1/2 kinase inhibitor). In mixed rat ventricular cardiomyocyte cultures, intra-ischemic application of esmolol, milrinone or esmolol + milrinone reduced myocyte death rates by 5.5%, 13.3%, and 16.8%, respectively, compared with saline (p < 0.01). This cell protective effect by esmolol + milrinone was abrogated in the presence of PKA-inhibitor or Akt-inhibitor. Esmolol, milrinone or esmolol + milrinone increased myocardial PKA activity by 22%, 28% and 59%, respectively, compared with saline (n = 6, p < 0.01). No non-specific adverse effect of Rp-cAMPS on myocytes was identified in a purified myocyte preparation during hypoxia/re-oxygenation. Antiapoptotic pathways were assessed by measuring myocardial phosphorylated Akt (pAkt) levels combined with terminal dUTP nick-end labelling staining analysis. Ten minutes following infusion of esmolol, milrinone or esmolol + milrinone, there were 1.7-, 2.7-, and 6-fold increase in tissue pAkt levels, respectively. This esmolol + milrinone induced pAkt activation was abolished in the presence of PKA inhibitor. Esmolol, milrinone and esmolol + milrinone reduced myocyte apoptosis rates by 22%, 37% and 60%, respectively, compared with saline (p < 0.01).
Late-ischemia/early reperfusion therapy with esmolol + milrinone additively reduces LV-IS associated with robust activation of myocardial PKA and subsequent Akt-antiapoptotic pathway.
本研究旨在探讨β（1）-肾上腺素能受体（AR）阻滞剂艾司洛尔和磷酸二酯酶 III 抑制剂米力农的晚期缺血/再灌注治疗是否能减少左心室（LV）心肌梗死面积（IS）。
在缺血/再灌注大鼠模型（30 分钟缺血/4 小时再灌注）中，艾司洛尔、米力农或艾司洛尔+米力农在 10 分钟内静脉（IV）输注（从缺血的最后 5 分钟到再灌注的最初 5 分钟）。生理盐水、艾司洛尔、米力农和艾司洛尔+米力农组的 LV-IS 分别为 48.9±8.9%、41.5±5.4%、25.8±7.7%和 16.8±7.3%（n=12/组）。与艾司洛尔或米力农单独治疗相比，艾司洛尔+米力农进一步降低了 LV-IS（p<0.05）。在存在蛋白激酶 A-（PKA）抑制剂（Rp-cAMPS）或 Akt 抑制剂（AKT 1/2 激酶抑制剂）的情况下，艾司洛尔+米力农诱导的 LV-IS 减少被消除。在缺血性心肌细胞培养物中，与生理盐水相比，艾司洛尔、米力农或艾司洛尔+米力农分别使心肌细胞死亡率降低 5.5%、13.3%和 16.8%（p<0.01）。在存在 PKA 抑制剂或 Akt 抑制剂的情况下，艾司洛尔+米力农的这种细胞保护作用被消除。与生理盐水相比，艾司洛尔、米力农或艾司洛尔+米力农分别使心肌 PKA 活性增加 22%、28%和 59%（n=6，p<0.01）。在纯化的心肌制剂中，在缺氧/再氧合期间，未发现 Rp-cAMPS 对心肌有非特异性的不良影响。通过测量心肌磷酸化 Akt（pAkt）水平并结合末端 dUTP 缺口末端标记染色分析来评估抗凋亡途径。在艾司洛尔、米力农或艾司洛尔+米力农输注 10 分钟后，组织 pAkt 水平分别增加了 1.7、2.7 和 6 倍。在存在 PKA 抑制剂的情况下，艾司洛尔+米力农诱导的 pAkt 激活被消除。与生理盐水相比，艾司洛尔、米力农和艾司洛尔+米力农分别使心肌细胞凋亡率降低 22%、37%和 60%（p<0.01）。
晚期缺血/再灌注治疗联合应用艾司洛尔+米力农可减少 LV-IS，与心肌 PKA 的强烈激活和随后的 Akt 抗凋亡途径有关。
