Mitochondrial calcium is thought to play an important role in the regulation of cardiac bioenergetics and function. The entry of calcium into the mitochondrial matrix requires that the divalent cation pass through the inner mitochondrial membrane via a specialized pore known as the mitochondrial calcium uniporter (MCU). Here, we use mice deficient of MCU expression to rigorously assess the role of mitochondrial calcium in cardiac function. Mitochondria isolated from MCU(-/-) mice have reduced matrix calcium levels, impaired calcium uptake and a defect in calcium-stimulated respiration. Nonetheless, we find that the absence of MCU expression does not affect basal cardiac function at either 12 or 20months of age. Moreover, the physiological response of MCU(-/-) mice to isoproterenol challenge or transverse aortic constriction appears similar to control mice. Thus, while mitochondria derived from MCU(-/-) mice have markedly impaired mitochondrial calcium handling, the hearts of these animals surprisingly appear to function relatively normally under basal conditions and during stress.

中文翻译：

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评估缺乏线粒体钙单向转运蛋白的小鼠的心功能。

线粒体钙被认为在调节心脏生物能和功能中起重要作用。钙进入线粒体基质需要二价阳离子通过称为线粒体钙单向转运蛋白（MCU）的专门孔穿过线粒体内膜。在这里，我们使用MCU表达不足的小鼠来严格评估线粒体钙在心脏功能中的作用。从MCU（-/-）小鼠中分离出的线粒体具有降低的基质钙水平，受损的钙摄取和钙刺激的呼吸缺陷。尽管如此，我们发现在12或20个月大时不存在MCU表达并不影响基础心脏功能。此外，MCU（-/-）小鼠对异丙肾上腺素激发或主动脉缩窄的生理反应似乎与对照小鼠相似。因此，虽然衍生自MCU（-/-）小鼠的线粒体显着损害了线粒体钙的处理能力，但这些动物的心脏却出乎意料地在基础条件下和压力下似乎相对正常地发挥功能。