Fischer U M, Klass O, Cox C S, Stock U, Antonyan A, Brixius K, Fischer J H, Mehlhorn U, Bloch W
Pediatric Surgery, University of Texas Medical School at Houston, Houston, Texas, United States of America.
Thorac Cardiovasc Surg. 2009 Oct;57(7):379-85. doi: 10.1055/s-0029-1185873. Epub 2009 Sep 30.
Nitric oxide (NO) production by both coronary endothelial cells and cardiomyocytes is thought to play a significant role in myocardial pathophysiology following ischemia/reperfusion (I/R).
In thirteen pigs subjected to 1 hour cardioplegic arrest (CA) on CPB, left ventricular (LV) biopsies were collected prior to CPB (baseline), at 60 min CPA, at 15 and 30 min reperfusion on CPB, and at 120 min post CPB. LV specimens were immunocytochemically stained against phospho-eNOS (Ser1177), phospho-eNOS (Thr495), phosphorylated ERK1/2, and AKT/PKB. Four additional pigs without CA served as controls. Cardiomyocytes were quantitatively investigated using TV densitometry (gray units: U).
After 60 min CA phosphorylation of eNOS (Ser1177) increased significantly and remained elevated until 30 min of reperfusion. In contrast, eNOS (Thr495) phosphorylation remained unchanged during CA and throughout reperfusion. In control animals, eNOS phosphorylation remained unchanged. Akt/PKB activity significantly increased after 60 min CA and decreased thereafter. ERK1/2 activity remained unchanged during ischemia but increased during reperfusion.
ENOS activation during ischemia occurs through phosphorylation at Ser1177 mediated by Akt/PKB. ERK1/2 does not seem to be involved in myocardial eNOS regulation especially not via phosphorylation at eNOS (Thr495).
冠状动脉内皮细胞和心肌细胞产生的一氧化氮（NO）被认为在缺血/再灌注（I/R）后的心肌病理生理学中起重要作用。
对13只在体外循环（CPB）下经历1小时心脏停搏（CA）的猪，在CPB前（基线）、CPB 60分钟时、CPB再灌注15和30分钟时以及CPB后120分钟采集左心室（LV）活检组织。LV标本进行免疫细胞化学染色，检测磷酸化eNOS（Ser1177）、磷酸化eNOS（Thr495）、磷酸化ERK1/2和AKT/PKB。另外4只未经历CA的猪作为对照。使用电视密度测定法（灰度单位：U）对心肌细胞进行定量研究。
CA 60分钟后，eNOS（Ser1177）的磷酸化显著增加，并一直升高到再灌注30分钟。相比之下，eNOS（Thr495）的磷酸化在CA期间和整个再灌注过程中保持不变。在对照动物中，eNOS磷酸化保持不变。Akt/PKB活性在CA 60分钟后显著增加，此后降低。ERK1/2活性在缺血期间保持不变，但在再灌注期间增加。
缺血期间eNOS的激活是通过Akt/PKB介导的Ser1177磷酸化实现的。ERK1/2似乎不参与心肌eNOS的调节，尤其是不通过eNOS（Thr495）的磷酸化。
