Beresewicz A, Czarnowska E, Maczewski M
Department of Clinical Physiology, Medical Centre of Postgraduate Education, Warsaw, Poland.
Mol Cell Biochem. 1998 Sep;186(1-2):87-97.
The effect of ischemic preconditioning and superoxide dismutase (SOD) on endothelial glycocalyx and endothelium-dependent vasodilation in the postischemic isolated guinea-pig hearts was examined. Seven groups of hearts were used: group 1 underwent sham aerobic perfusion; group 2 was subjected to 40 min global ischemia without reperfusion; group 3, 40 min ischemia followed by 40 min reperfusion; group 4 was preconditioned with three cycles of 5 min global ischemia followed by 5 min of reperfusion (IPC), prior to 40 min ischemia; group 5 was subjected to IPC prior to standard ischemia/ reperfusion; group 6 underwent standard ischemia/reperfusion and SOD infusion (150 U/ml) was begun 5 min before 40 min ischemia and continued during the initial 5 min of the reperfusion period; group 7 was subjected to 80 min aerobic perfusion with NO-synthase inhibitor, L-NAME, to produce a model of endothelial dysfunction independent from the ischemia/reperfusion. Coronary flow responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were used as measures of endothelium-dependent and endothelium-independent vascular function, respectively. Reduction in coronary flow caused by NO-synthase inhibitor, L-NAME, served as a measure of a basal endothelium-dependent vasodilator tone. After completion of each experimental protocol, the hearts were stained with ruthenium red or lanthanum chloride for electron microscopy evaluation of the endothelial glycocalyx. While ischemia led only to a slightly flocculent appearance of the glycocalyx, in ischemia/reperfused hearts the glycocalyx was disrupted, suggesting that it is the reperfusion injury which leads to the glycocalyx injury. Moreover, the coronary flow responses to ACh and L-NAME were impaired, while the responses to SNP were unchanged in the ischemia/reperfused hearts. The disruption of the glycocalyx and the deterioration of ACh and L-NAME responses was prevented by IPC. In addition, the alterations in the glycocalyx and the impairment of ACh responses were prevented by SOD. The glycocalyx appeared to be not changed in the hearts subjected to 80 min aerobic perfusion with L-NAME.
(1) the impairment of the endothelium-dependent coronary vasodilation is paralleled by the endothelial glycocalyx disruption in the postischemic guinea-pig hearts; (2) both these changes are prevented by SOD, suggesting the role of free radicals in the mechanism of their development; (3) both changes are prevented by IPC. We hypothesize, therefore, that alterations in the glycocalyx contribute to the mechanism of the endothelial dysfunction in the postischemic hearts.
研究了缺血预处理和超氧化物歧化酶（SOD）对缺血后离体豚鼠心脏内皮糖萼和内皮依赖性血管舒张的影响。使用了七组心脏：第1组进行假有氧灌注；第2组进行40分钟全心缺血且无再灌注；第3组，40分钟缺血后再灌注40分钟；第4组在40分钟缺血前进行三个周期的5分钟全心缺血后再灌注5分钟（缺血预处理）；第5组在标准缺血/再灌注前进行缺血预处理；第6组进行标准缺血/再灌注，并在40分钟缺血前5分钟开始输注SOD（150 U/ml），并在再灌注期的最初5分钟持续输注；第7组用一氧化氮合酶抑制剂L-NAME进行80分钟有氧灌注，以建立独立于缺血/再灌注的内皮功能障碍模型。分别用冠状动脉对乙酰胆碱（ACh）和硝普钠（SNP）的血流反应来衡量内皮依赖性和非内皮依赖性血管功能。用一氧化氮合酶抑制剂L-NAME引起的冠状动脉血流减少作为基础内皮依赖性血管舒张张力的指标。完成每个实验方案后，用钌红或氯化镧对心脏进行染色，以通过电子显微镜评估内皮糖萼。虽然缺血仅导致糖萼出现轻微絮状外观，但在缺血/再灌注心脏中糖萼被破坏，这表明是再灌注损伤导致了糖萼损伤。此外，缺血/再灌注心脏中对ACh和L-NAME的冠状动脉血流反应受损，而对SNP的反应未改变。缺血预处理可防止糖萼破坏以及ACh和L-NAME反应的恶化。此外，SOD可防止糖萼改变和ACh反应受损。在用L-NAME进行80分钟有氧灌注的心脏中，糖萼似乎未发生变化。
（1）缺血后豚鼠心脏中内皮依赖性冠状动脉舒张功能受损与内皮糖萼破坏同时出现；（2）这两种变化均被SOD阻止，表明自由基在其发生机制中起作用；（3）这两种变化均被缺血预处理阻止。因此，我们推测糖萼的改变促成了缺血后心脏内皮功能障碍的机制。
