Department of Physiology and Pathophysiology, Peking University Health Science Center, 38 Xue Yuan Road, Beijing, 100191, China.
Pflugers Arch. 2012 Feb;463(2):257-68. doi: 10.1007/s00424-011-1040-4. Epub 2011 Oct 22.
The present study was to determine the role of the type I isoform of cGMP-dependent protein kinase (PKG I) and its downstream effector myosin phosphatase target subunit 1 (MYPT1) in the responses of different sized coronary arteries to nitrovasodilators. Relaxations of isolated porcine coronary arteries were determined by isometric tension recording technique. Protein levels of PKG I and its effectors were analyzed by Western blotting. The activities of PKG I and MYPT1 were studied by analyzing phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and MYPT1, respectively. Nitroglycerin, DETA NONOate, and 8-Br-cGMP caused greater relaxations in large than in small coronary arteries. Relaxations were attenuated to a greater extent by Rp-8-Br-PET-cGMPS (a PKG inhibitor) in large vs. small arteries. The expressions of PKG I and MYPT1 in large arteries were more abundant than in small arteries. DETA NONOate stimulated phosphorylation of VASP at Ser239 and inhibited phosphorylation of MYPT1 at Thr853 to a greater extent in large than in small arteries. A suppressed phosphorylation of MYPT1 at Thr853 was caused by 8-Br-cGMP in large but not small arteries, which was inhibited by Rp-8-Br-PET-cGMPS. These results suggest that the greater responsiveness of large coronary arteries to nitrovasodilators result in part from greater activities of PKG I and MYPT1. Dysfunction in nitric oxide signaling is implicated in the vulnerability of large coronary arteries to certain disorders such as atherosclerosis and spasm. Augmentation of PKG I-MYPT1 signaling may be of therapeutic benefit for combating these events.
本研究旨在确定 I 型环鸟苷酸依赖性蛋白激酶（PKG I）及其下游效应物肌球蛋白磷酸酶靶亚单位 1（MYPT1）在不同大小的冠状动脉对硝基血管扩张剂反应中的作用。通过等长张力记录技术测定分离的猪冠状动脉的松弛度。通过 Western blot 分析 PKG I 及其效应物的蛋白水平。通过分别分析血管扩张刺激磷酸蛋白（VASP）和 MYPT1 的磷酸化来研究 PKG I 和 MYPT1 的活性。硝酸甘油、DETA NONOate 和 8-Br-cGMP 引起的大冠状动脉舒张大于小冠状动脉。与小动脉相比，大冠状动脉中 Rp-8-Br-PET-cGMPS（PKG 抑制剂）对舒张的抑制作用更大。大动脉中 PKG I 和 MYPT1 的表达比小动脉更丰富。DETA NONOate 刺激 VASP 在 Ser239 的磷酸化，并比小动脉更大程度地抑制 MYPT1 在 Thr853 的磷酸化。8-Br-cGMP 在大冠状动脉中但不在小冠状动脉中引起 MYPT1 在 Thr853 的磷酸化受到抑制，这被 Rp-8-Br-PET-cGMPS 抑制。这些结果表明，大冠状动脉对硝基血管扩张剂的反应性增强部分归因于 PKG I 和 MYPT1 的活性增强。一氧化氮信号转导功能障碍与某些疾病（如动脉粥样硬化和痉挛）大冠状动脉的易感性有关。增强 PKG I-MYPT1 信号可能对对抗这些事件具有治疗益处。
