金缕梅酚-C通过增强大鼠心室肌细胞肌浆网钙负载及经由蛋白激酶C的释放来增加收缩力。
Chrysosplenol-C Increases Contraction by Augmentation of Sarcoplasmic Reticulum Ca Loading and Release via Protein Kinase C in Rat Ventricular Myocytes.
作者信息
Wang J, Trinh T N, Vu A T V, Kim J C, Hoang A T N, Ohk C J, Zhang Y H, Nguyen C M, Woo S H
机构信息
Pathophysiology Laboratory, College of Pharmacy, Chungnam National University, Yuseong-gu, Daejeon, South Korea (J.W., T.N.T., A.T.V.V., S.H.W.); NEXEL Co., Ltd. 8F, 55 Magokdong-ro, Gangseo-gu, Seoul, South Korea (J.C.K.); Institute of Natural Products Chemistry, VAST, Hanoi, Vietnam (A.T.N.H., C.M.N.); and Department of Physiology and Biomedical Sciences, College of Medicine, Seoul National University, Jongro-gu, Seoul, South Korea (C.J.O., Y.H.Z.).
Pathophysiology Laboratory, College of Pharmacy, Chungnam National University, Yuseong-gu, Daejeon, South Korea (J.W., T.N.T., A.T.V.V., S.H.W.); NEXEL Co., Ltd. 8F, 55 Magokdong-ro, Gangseo-gu, Seoul, South Korea (J.C.K.); Institute of Natural Products Chemistry, VAST, Hanoi, Vietnam (A.T.N.H., C.M.N.); and Department of Physiology and Biomedical Sciences, College of Medicine, Seoul National University, Jongro-gu, Seoul, South Korea (C.J.O., Y.H.Z.)
出版信息
Mol Pharmacol. 2022 Jan;101(1):13-23. doi: 10.1124/molpharm.121.000365. Epub 2021 Nov 11.
Naturally found chrysosplenol-C (4',5,6-trihydroxy-3,3',7-trimethoxyflavone) increases the contractility of cardiac myocytes independent of -adrenergic signaling. We investigated the cellular mechanism for chrysosplenol-C-induced positive inotropy. Global and local Ca signals, L-type Ca current (I), and contraction were measured from adult rat ventricular myocytes using two-dimensional confocal Ca imaging, the whole-cell patch-clamp technique, and video-edge detection, respectively. Application of chrysosplenol-C reversibly increased Ca transient magnitude with a maximal increase of ∼55% within 2- to 3-minute exposures (EC ≅ 21 μM). This chemical did not alter I and slightly increased diastolic Ca level. The frequency and size of resting Ca sparks were increased by chrysosplenol-C. Chrysosplenol-C significantly increased sarcoplasmic reticulum (SR) Ca content but not fractional release. Pretreatment of protein kinase C (PKC) inhibitor but not Ca/calmodulin-dependent protein kinase II (CaMKII) inhibitor abolished the stimulatory effects of chrysosplenol-C on Ca transients and Ca sparks. Chrysosplenol-C-induced positive inotropy was removed by the inhibition of PKC but not CaMKII or phospholipase C. Western blotting assessment revealed that PKC- protein level in the membrane fractions significantly increase within 2 minutes after chrysosplenol-C exposure with a delayed (5-minute) increase in PKC- levels in insoluble membrane. These results suggest that chrysosplenol-C enhances contractility via PKC (most likely PKC-)-dependent enhancement of SR Ca releases in ventricular myocytes. SIGNIFICANCE STATEMENT: Study shows that chrysosplenol-C, a natural flavone showing a positive inotropic effect, increases SR Ca releases on depolarizations and Ca sparks with an increase of SR Ca loading but not L-type Ca current in ventricular myocytes. Chrysosplenol-C-induced enhancement in contraction is eliminated by PKC inhibition, and it is associated with redistributions of PKC to the membrane. These indicate that chrysosplenol-C enhances contraction via PKC-dependent augmentations of SR Ca release and Ca loading during action potentials.
天然存在的金耳草酚 - C（4',5,6 - 三羟基 - 3,3',7 - 三甲氧基黄酮）可增强心肌细胞的收缩力，且不依赖于β - 肾上腺素能信号传导。我们研究了金耳草酚 - C诱导正性肌力作用的细胞机制。分别使用二维共聚焦钙成像、全细胞膜片钳技术和视频边缘检测，从成年大鼠心室肌细胞中测量整体和局部钙信号、L型钙电流（I）以及收缩情况。应用金耳草酚 - C可使钙瞬变幅度可逆性增加，在2至3分钟的暴露时间内最大增加约55%（半数有效浓度≅21μM）。这种化学物质不会改变I，且略微增加舒张期钙水平。金耳草酚 - C可增加静息钙火花的频率和大小。金耳草酚 - C显著增加肌浆网（SR）钙含量，但不增加钙的分数释放。蛋白激酶C（PKC）抑制剂预处理可消除金耳草酚 - C对钙瞬变和钙火花的刺激作用，而钙/钙调蛋白依赖性蛋白激酶II（CaMKII）抑制剂预处理则无此作用。抑制PKC可消除金耳草酚 - C诱导的正性肌力作用，而抑制CaMKII或磷脂酶C则无此作用。蛋白质印迹评估显示，金耳草酚 - C暴露后2分钟内，膜组分中PKC - 的蛋白水平显著增加，不溶性膜中PKC - 水平在5分钟后延迟增加。这些结果表明，金耳草酚 - C通过PKC（最可能是PKC - ）依赖性增强心室肌细胞中SR钙释放来增强收缩力。意义声明：研究表明，具有正性肌力作用的天然黄酮金耳草酚 - C可增加去极化时的SR钙释放和钙火花，同时增加SR钙负荷，但不增加心室肌细胞中的L型钙电流。PKC抑制可消除金耳草酚 - C诱导的收缩增强作用，且这与PKC向膜的重新分布有关。这些表明金耳草酚 - C通过PKC依赖性增强动作电位期间的SR钙释放和钙负荷来增强收缩力。
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