Morimoto Satoshi, O-Uchi Jin, Kawai Makoto, Hoshina Toshiyuki, Kusakari Yoichiro, Komukai Kimiaki, Sasaki Hiroyuki, Hongo Kenichi, Kurihara Satoshi
Department of Cell Physiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan.
Biochem Biophys Res Commun. 2009 Dec 4;390(1):87-92. doi: 10.1016/j.bbrc.2009.09.071. Epub 2009 Sep 23.
In heart failure, chronic catecholaminergic stimulation increases diastolic Ca(2+) leak from ryanodine receptors (RyRs) of sarcoplasmic reticulum (SR), possibly due to the phosphorylation of RyRs through the activation of protein kinase A (PKA) or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). In the present study, we attempted to identify which activated kinase is responsible for the enhanced Ca(2+) leak caused by beta-adrenergic stimulation. Trabeculae obtained from the hearts of adult male C57BL/6J mice were treated with isoproterenol and then permeabilized with saponin. To examine SR functions, Ca(2+) in SR was released with caffeine and measured with fluo-3. The Ca(2+) leak in isoproterenol-treated preparations was significantly increased when the PKA-dependent phosphorylation of RyR was increased without the involvement of CaMKII-dependent phosphorylation. Both the increase in Ca(2+) leak and the phosphorylation of RyR were blocked by a PKA inhibitor. Our results show that beta-adrenergic stimulation increases Ca(2+) leak from SR through PKA-dependent phosphorylation of RyR.
在心力衰竭中，慢性儿茶酚胺能刺激会增加肌浆网（SR）中兰尼碱受体（RyRs）的舒张期Ca(2+)泄漏，这可能是由于通过蛋白激酶A（PKA）或Ca(2+)/钙调蛋白依赖性蛋白激酶II（CaMKII）的激活导致RyRs磷酸化所致。在本研究中，我们试图确定哪种激活的激酶负责β-肾上腺素能刺激引起的Ca(2+)泄漏增强。从成年雄性C57BL/6J小鼠心脏获取的小梁用异丙肾上腺素处理，然后用皂角苷使其通透。为了检测SR功能，用咖啡因释放SR中的Ca(2+)并用fluo-3进行测量。当RyR的PKA依赖性磷酸化增加而不涉及CaMKII依赖性磷酸化时，异丙肾上腺素处理的制剂中的Ca(2+)泄漏显著增加。Ca(2+)泄漏的增加和RyR的磷酸化均被PKA抑制剂阻断。我们的结果表明，β-肾上腺素能刺激通过RyR的PKA依赖性磷酸化增加SR的Ca(2+)泄漏。
