L-Carnitine (L-C) is a conditionally essential nutrient required for β-oxidation and cell energy production whose unbalanced metabolism is associated with a variety of diseases. L-C increased cell proliferation, differentiation and mineralization of human osteoblast in culture. The present study evaluated the effect of L-C on intracellular calcium signaling, an important modulator of cell proliferation and differentiation in human osteoblasts by means of Fura-2 fluorescence coupled to video imaging technique. 5 mM L-C promoted a calcium influx from the extracellular milieu by depolarizing L-type calcium channels. Moreover, L-C depleted the calcium stores of the mitochondria and of the endoplasmic reticulum through phospholipase C activation. The inhibition of the calcium sensing receptor with 10 µM NPS-2143 prevented the L-C dependent cytosolic calcium increase suggesting that this calcium mobilization is mediated by Calcium Sensing Receptor activation. These results unravel that L-C might be part of a complex nutritional environment which tunes osteoblast activity.

左旋肉碱（LC）是β-氧化和细胞能量产生所需的条件必需营养素，其代谢失衡与多种疾病有关。LC增加了培养物中人成骨细胞的细胞增殖，分化和矿化作用。本研究通过Fura-2荧光和视频成像技术评估了LC对细胞内钙信号传导的影响，钙信号传导是人类成骨细胞中细胞增殖和分化的重要调节剂。5 mM LC通过使L型钙通道去极化来促进钙从细胞外环境中涌​​入。此外，LC通过磷脂酶C的激活耗尽了线粒体和内质网的钙存储。用10 µM NPS-2143抑制钙敏感受体可防止LC依赖性胞质钙增加，表明该钙动员是由钙敏感受体激活介导的。这些结果表明，LC可能是调节成骨细胞活性的复杂营养环境的一部分。