Calcium-induced calcium release Calcium-induced calcium release Calcium-induced calcium release (CICR) describes a biological process whereby calcium is able to activate calcium release from intracellular Ca stores (e.g., endoplasmic reticulum or sarcoplasmic reticulum). Although CICR was first proposed for skeletal muscle in the 1970s, it is now known that CICR is unlikely to be its primary mechanism for activating SR calcium release. Instead, CICR is thought to be crucial for excitation-contraction coupling in cardiac muscle and it is now obvious that CICR is a widely occurring cellular signaling process present even in many non-muscle cells, e.g. in the insulin-secreting pancreatic beta cells and many
Calcium About three-quarters of dietary calcium is from dairy products and grains, the rest being accounted for by vegetables, protein-rich foods, fruits, sugar, fats, and oil. Calcium supplementation is controversial, as the bioavailability of calcium is strongly dependent on the solubility of the salt involved: calcium citrate, malate, and lactate are highly bioavailable while the oxalate is much less so. The intestine absorbs about one-third of calcium eaten as the free ion, and plasma calcium level is then regulated by the kidneys. Parathyroid hormone and vitamin D promote the formation of bone by allowing and enhancing the deposition of calcium ions