“Calcium-induced calcium release”的意思、由来-开放百科全书

Calcium-induced calcium release (CICR) describes a biological process whereby calcium is able to activate calcium release from intracellular Ca²⁺ stores (e.g., endoplasmic reticulum or sarcoplasmic reticulum). Although CICR was first proposed for skeletal muscle in the 1970s,^[1] 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^[2] 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^[3] and many other cells. Since CICR is a positive-feedback system, it has been of great interest to elucidate the mechanism(s) responsible for its termination.

Examples in biology

Excitation-contraction coupling

Excitation-contraction coupling in myocardium relies on sarcolemma depolarization and subsequent Ca²⁺ entry to trigger Ca²⁺ release from the sarcoplasmic reticulum. When an action potential depolarizes the cell membrane, voltage-gated Ca²⁺ channels (e.g., L-type calcium channels) are activated. CICR occurs when the resulting Ca²⁺ influx activates ryanodine receptors on the SR membrane, which causes more Ca²⁺ to be released into the cytosol. In cardiac muscle, the result of CICR is observed as a spatio-temporally restricted Ca²⁺ spark. The result of CICR across the cell causes the significant increase in cytosolic Ca²⁺ that is important in activating muscle contraction.

References

1. ^{{cite journal |pmid=13441 |year=1977 |last1=Endo |first1=M |title=Calcium release from the sarcoplasmic reticulum |volume=57 |issue=1 |pages=71–108 |journal=Physiological Reviews}}
2. ^{{cite journal |volume=245 |issue=1 |pages=C1-14 |title=Calcium-induced calcium release from the cardiac sarcoplasmic reticulum |year=1983 |author=Fabiato, A. |journal=American Journal of Physiology |pmid=6346892}}
3. ^{{cite journal |pages=287–91 |doi=10.1016/0014-5793(92)80306-2 |title=Ca2+-induced Ca2+ release in insulin-secreting cells |year=1992 |last1=Islam |first1=Md.Shahidul |last2=Rorsman |first2=Patrik |last3=Berggren |first3=Per-Olof |journal=FEBS Letters |volume=296 |issue=3 |pmid=1537406}}