Department of Clinical and Biological Sciences, University of Torino, Orbassano, Italy.
J Surg Res. 2013 Jul;183(1):111-8. doi: 10.1016/j.jss.2012.12.029. Epub 2013 Jan 8.
Acidic perfusion (AP) performed at the onset of reperfusion (i.e., acid postconditioning) is cardioprotective. We investigated the effect of AP on postischemic cardiac function and on the activity of endogenous superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase. The role of exogenous CAT or SOD on AP cardioprotection was also investigated. Phosphorylation of redox-sensitive survival kinases (protein kinase C [PKC] ε and extracellular signal-regulated kinase [ERK] 1/2) was also checked.
Isolated rat hearts underwent ischemia and reperfusion (I/R) for 30 and 120 min, respectively. AP was obtained by lowering [HCO3(-)] in the perfusion buffer. Infarct size and left ventricular pressure were measured. Protocols include I/R only, I/R plus acidic perfusion in early reperfusion (I/R + AP), and I/R plus AP and CAT (I/R + AP + CAT) or SOD (I/R + AP + SOD). I/R + SOD and I/R + CAT additional hearts served as controls. AP and/or antioxidants were given in the initial 3 min of reperfusion. Enzyme activities were studied in postischemic phase (seventh minute of reperfusion) in I/R or I/R + AP and Sham (buffer-perfused) hearts.
AP with (I/R + AP + CAT or I/R + AP + SOD) or without (I/R + AP) antioxidant enzymes resulted in a larger reduction of infarct size compared with I/R, I/R + SOD, or I/R + CAT. Compared with I/R, the postischemic systolic and diastolic recoveries of the cardiac function were markedly improved by the addition of AP and a lesser extent by AP + SOD or AP + CAT. AP increased the postischemic activity of CAT and lowered that of SOD and glutathione peroxidase compared with I/R only. Also, the phosphorylation and activity of ERK1/2 and PKCε were increased by AP.
Acid postconditioning affects the activity of endogenous antioxidant enzymes, activates ERK1/2-PKCε pathways, and protects against myocardial I/R injury. The combination of AP and exogenous SOD or CAT still provides cardioprotection. It is likely that intracellular (not extracellular) redox condition plays a pivotal role in acidic protection.
再灌注时进行酸性灌流（AP）（即酸后处理）具有心脏保护作用。我们研究了 AP 对缺血后心功能的影响，以及对内源性超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶活性的影响。还研究了外源性 CAT 或 SOD 对 AP 心脏保护作用的影响。检查了氧化还原敏感生存激酶（蛋白激酶 C[PKC]ε和细胞外信号调节激酶[ERK]1/2）的磷酸化。
分离的大鼠心脏经历缺血和再灌注（I/R）分别为 30 和 120 分钟。AP 通过降低灌注缓冲液中的[HCO3(-)]获得。测量梗塞面积和左心室压力。方案包括仅 I/R、I/R 加早期再灌注时的酸性灌注（I/R+AP）以及 I/R 加 AP 和 CAT（I/R+AP+CAT）或 SOD（I/R+AP+SOD）。I/R+SOD 和 I/R+CAT 附加心脏作为对照。AP 和/或抗氧化剂在再灌注的最初 3 分钟内给予。在 I/R 或 I/R+AP 和 Sham（缓冲液灌注）心脏的缺血后阶段（再灌注的第七分钟）研究酶活性。
与 I/R、I/R+SOD 或 I/R+CAT 相比，AP 加（I/R+AP+CAT 或 I/R+AP+SOD）或不加（I/R+AP）抗氧化酶可更大程度地减少梗塞面积。与 I/R 相比，AP 的加入明显改善了缺血后心脏功能的收缩和舒张恢复，而 AP+SOD 或 AP+CAT 的改善程度较小。与仅 I/R 相比，AP 增加了缺血后 CAT 的活性，降低了 SOD 和谷胱甘肽过氧化物酶的活性。此外，AP 还增加了 ERK1/2 和 PKCε的磷酸化和活性。
酸后处理影响内源性抗氧化酶的活性，激活 ERK1/2-PKCε 途径，防止心肌 I/R 损伤。AP 与外源性 SOD 或 CAT 的联合仍提供心脏保护。很可能细胞内（而非细胞外）氧化还原条件在酸性保护中起关键作用。
