And meanwhile, those calcium pumps are working hard to restock the calcium in the sarcoplasmic reticulum.

与此同时，这些钙努力补充肌浆网中的钙。

Its walls are loaded with calcium pumps — which use ATP to save up a bunch of calcium ions.

它的壁上装有钙——它使用三磷酸腺苷来储存一堆钙离子。

That tension means myosin and the calcium pumps are burning up the muscle cells' ATP, and the finite supply of ATP is what makes it impossible to maintain vigorous muscle activity indefinitely.

这种张力意味着肌球蛋白和钙燃烧肌肉细胞的三磷酸腺苷，而三磷酸腺苷的有限供应使得肌肉活动不可能无限期地保持旺盛。