Kobayashi M, Shoji N, Ohizumi Y
Mitsubishi-Kasei Institute of Life Sciences, Tokyo, Japan.
Biochim Biophys Acta. 1987 Sep 18;903(1):96-102. doi: 10.1016/0005-2736(87)90159-3.
Gingerol, isolated as a potent cardiotonic agent from the rhizome of ginger, stimulated the Ca2+-pumping activity of fragmented sarcoplasmic reticulum (SR) prepared from rabbit skeletal and dog cardiac muscles. The extravesicular Ca2+ concentrations of the heavy fraction of the fragmented SR (HSR) were measured directly with a Ca2+ electrode to examine the effect of gingerol on the SR. Gingerol (3-30 microM) accelerated the Ca2+-pumping rate of skeletal and cardiac SR in a concentration-dependent manner. The rate of 45Ca2+ uptake of HSR was also increased markedly by 30 microM gingerol without affecting the 45Ca2+ efflux from HSR. Furthermore, gingerol activated Ca2+-ATPase activities of skeletal and cardiac SR (EC50, 4 microM). The activation of SR Ca2+-ATPase activity by gingerol (30 microM) was completely reversed by 100-fold dilution with the fresh saline solution. Kinetic analysis of activating effects of gingerol suggests that the activation of SR Ca2+-ATPase is uncompetitive and competitive with respect to Mg . ATP at concentrations of 0.2-0.5 mM and above 1 mM, respectively. Kinetic analysis also suggests that the activation by gingerol is mixed-type with respect to free Ca2+ and this enzyme is activated probably due to the acceleration of enzyme-substrate complex breakdown. Gingerol had no significant effect on sarcolemmal Ca2+-ATPase, myosin Ca2+-ATPase, actin-activated myosin ATPase and cAMP-phosphodiesterase activities, indicating that the effect of gingerol is rather specific to SR Ca2+-ATPase activity. Gingerol may provide a valuable chemical tool for studies aimed at clarifying the regulatory mechanisms of SR Ca2+-pumping systems and the causal relationship between the Ca2+-pumping activity of SR and muscle contractility.
姜辣素是从姜的根茎中分离出的一种有效的强心剂，它能刺激从兔骨骼肌和犬心肌制备的肌浆网（SR）片段的Ca2+泵浦活性。用Ca2+电极直接测量破碎SR重组分（HSR）的囊泡外Ca2+浓度，以研究姜辣素对SR的影响。姜辣素（3 - 30 microM）以浓度依赖的方式加速骨骼肌和心肌SR的Ca2+泵浦速率。30 microM姜辣素也显著提高了HSR对45Ca2+的摄取速率，而不影响HSR中45Ca2+的流出。此外，姜辣素激活了骨骼肌和心肌SR的Ca2+-ATP酶活性（EC50，4 microM）。用新鲜盐溶液稀释100倍可完全逆转姜辣素（30 microM）对SR Ca2+-ATP酶活性的激活作用。姜辣素激活作用的动力学分析表明，SR Ca2+-ATP酶的激活在0.2 - 0.5 mM浓度下对Mg.ATP是非竞争性的，在1 mM以上浓度下是竞争性的。动力学分析还表明，姜辣素对游离Ca2+的激活是混合型的，该酶可能由于酶-底物复合物分解的加速而被激活。姜辣素对肌膜Ca2+-ATP酶、肌球蛋白Ca2+-ATP酶、肌动蛋白激活的肌球蛋白ATP酶和cAMP-磷酸二酯酶活性无显著影响，表明姜辣素对SR Ca2+-ATP酶活性的作用具有相当的特异性。姜辣素可能为旨在阐明SR Ca2+泵浦系统调节机制以及SR Ca2+泵浦活性与肌肉收缩性之间因果关系的研究提供一种有价值的化学工具。
