Strniskova Monika, Barancik Miroslav, Neckar Jan, Ravingerova Tanya
Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Mol Cell Biochem. 2003 Jul;249(1-2):59-65.
Diabetes mellitus (DM) causes myocardial remodeling on the subcellular level and alterations in the function of the cell membranes ion transport systems resulting in contractile dysfunction. The present study was aimed to investigate the expression and activation of mitogen-activated protein kinases (MAPKs) and their possible role in the acute diabetic rat hearts. Rats were injected with single dose of streptozotocin (45 mg/kg, i.v.), and after 1 week the disease was manifested by hyperglycemia and cardiac dysfunction. The Langendorff-perfused hearts were subjected to ischemia (5 or 30 min occlusion of LAD coronary artery). The protein pattern in cytosolic fraction of the heart tissue was determined after electrophoretic separation. The levels and activation of MAPKs were determined by Western blot analysis using specific antibodies. No differences between the diabetics and controls in the level of ERKs were found at baseline. However, in DM samples ERKs phosphorylation was markedly increased, and further changes occurred during ischemia. Also content of phoshorylated c-Raf kinase (an upstream activator of ERKs) was slightly increased at baseline conditions in the diabetic samples. In contrast, no significant changes in the contents and phosphorylation of p38-MAPK were observed at baseline. But some differences in the p38-MAPK phosphorylation were found during ischemia. The results show that differential pattern of protein kinase cascades activation in the diabetic hearts might be account for the modulation of their response to ischemia.
糖尿病（DM）会在亚细胞水平上引起心肌重塑，并导致细胞膜离子转运系统功能改变，进而引发收缩功能障碍。本研究旨在探讨丝裂原活化蛋白激酶（MAPKs）在急性糖尿病大鼠心脏中的表达和激活情况及其可能发挥的作用。给大鼠单次静脉注射链脲佐菌素（45 mg/kg），1周后出现高血糖和心脏功能障碍，以此作为疾病模型。将采用Langendorff灌注的心脏进行缺血处理（结扎左冠状动脉5分钟或30分钟）。通过电泳分离后测定心脏组织胞质部分的蛋白质图谱。使用特异性抗体通过蛋白质印迹分析来测定MAPKs的水平和激活情况。在基线时，糖尿病组和对照组之间的细胞外信号调节激酶（ERKs）水平没有差异。然而，在糖尿病样本中，ERKs的磷酸化显著增加，并且在缺血过程中进一步发生变化。此外，在糖尿病样本的基线条件下，磷酸化的c-Raf激酶（ERKs的上游激活剂）含量略有增加。相比之下，在基线时未观察到p38丝裂原活化蛋白激酶（p38-MAPK）的含量和磷酸化有显著变化。但在缺血过程中发现p38-MAPK的磷酸化存在一些差异。结果表明，糖尿病心脏中蛋白激酶级联激活的差异模式可能是其对缺血反应调节的原因。
