Calcium metabolism Calcium metabolism Calcium metabolism refers to the movements and regulation of calcium ions (Ca) "in" and "out" of various body compartments, such as the gastrointestinal tract, the blood plasma, the extracellular and intracellular fluids, and bone tissue. An important aspect of calcium metabolism is plasma calcium homeostasis, the regulation of calcium ions in the blood plasma within narrow limits. In this process, bone tissue acts as a calcium storage center for deposits and withdrawals as needed by the blood, via continual bone remodeling. Derangement of this mechanism leads to hypercalcemia or hypocalcemia, both of which can have consequences for health.
Mitochondrial calcium uniporter Calcium is balanced through the MCU in conjunction with the sodium-calcium exchanger. The MCU has a very low affinity for calcium, so the cytosolic calcium concentration needs to be approximately 5-10 uM for significant transport of calcium into the mitochondria. Mitochondria are closely associated with the endoplasmic reticulum (ER), at contact sites, which contains stores of cellular calcium ions for calcium signaling. The presence of 1,4,5-triphosphate (IP) triggers the release of calcium from these intracellular stores, which creates microdomains of high calcium concentration between the ER and the mitochondria, creating the conditions for the MCU to take up calcium. Ruthenium