The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel.
Mol Cell Biochem. 2010 Dec;345(1-2):153-60. doi: 10.1007/s11010-010-0568-5. Epub 2010 Aug 22.
Activation of either the A(1) adenosine receptor (A(1)R) or the A(3) adenosine receptor (A(3)R), by their specific agonists CCPA and Cl-IB-MECA, respectively, protects cardiac cells in culture against ischemic injury. Yet the full protective mechanism remains unclear. In this study, we therefore examined the involvement of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK) phosphorylation in this protective intracellular signaling mechanism. Furthermore, we investigated whether p38 MAPK phosphorylation occurs upstream or downstream from the opening of mitochondrial ATP-sensitive potassium (K(ATP)) channels. The role of p38 MAPK activation in the intracellular signaling process was studied in cultured cardiomyocytes subjected to hypoxia, that were pretreated with CCPA or Cl-IB-MECA or diazoxide (a mitochondrial K(ATP) channel opener) with and without SB203580 (a specific inhibitor of phosphorylated p38 MAPK). Cardiomyocytes were also pretreated with anisomycin (p38 MAPK activator) with and without 5-hydroxy decanoic acid (5HD) (a mitochondrial K(ATP) channel blocker). SB203580 together with the CCPA, Cl-IB-MECA or diazoxide abrogated the protection against hypoxia as shown by the level of ATP, lactate dehydrogenase (LDH) release, and propidium iodide (PI) staining. Anisomycin protected the cardiomyocytes against ischemic injury and this protection was abrogated by SB203580 but not by 5HD. Conclusions Activation of A(1)R or A(3)R by CCPA or Cl-IB-MECA, respectively, protects cardiomyocytes from hypoxia via phosphorylation of p38 MAPK, which is located downstream from the mitochondrial K(ATP) channel opening. Elucidating the signaling pathway by which adenosine receptor agonists protect cardiomyocytes from hypoxic damage, will facilitate the development of anti ischemic drugs.
激动剂 CCPA 和 Cl-IB-MECA 分别激活 A(1)腺苷受体（A(1)R）和 A(3)腺苷受体（A(3)R），可保护培养的心肌细胞免受缺血性损伤。然而，完整的保护机制尚不清楚。因此，在本研究中，我们研究了 p38 丝裂原活化蛋白激酶（MAPK）和细胞外信号调节激酶（ERK）磷酸化在这种保护性细胞内信号转导机制中的作用。此外，我们还研究了 p38 MAPK 磷酸化是否发生在线粒体 ATP 敏感性钾（K(ATP)）通道开放的上游或下游。在缺氧条件下培养的心肌细胞中，研究了 p38 MAPK 激活在细胞内信号转导过程中的作用，这些细胞用 CCPA 或 Cl-IB-MECA 或二氮嗪（线粒体 K(ATP)通道开放剂）预处理，并在有和没有 SB203580（磷酸化 p38 MAPK 的特异性抑制剂）的情况下进行处理。心肌细胞也用放线菌酮（p38 MAPK 激活剂）预处理，并在有和没有 5-羟基癸酸（5HD）（线粒体 K(ATP)通道阻滞剂）的情况下进行处理。SB203580 与 CCPA、Cl-IB-MECA 或二氮嗪一起消除了对缺氧的保护作用，如 ATP 水平、乳酸脱氢酶（LDH）释放和碘化丙啶（PI）染色所示。放线菌酮可保护心肌细胞免受缺血性损伤，这种保护作用被 SB203580 消除，但被 5HD 消除。结论激动剂 CCPA 或 Cl-IB-MECA 分别激活 A(1)R 或 A(3)R，通过线粒体 K(ATP)通道开放后的 p38 MAPK 磷酸化，保护心肌细胞免受缺氧。阐明腺苷受体激动剂保护心肌细胞免受缺氧损伤的信号通路，将有助于开发抗缺血药物。
