Sarco-Endoplasmic Reticulum Calcium Release Model Based on Changes in the Luminal Calcium Content.

The sarcoplasmic/endoplasmic reticulum (SR/ER) is the main intracellular calcium (Ca) pool in muscle and non-muscle eukaryotic cells, respectively. The reticulum accumulates Ca against its electrochemical gradient by the action of sarco/endoplasmic reticulum calcium ATPases (SERCA pumps), and the capacity of this Ca store is increased by the presence of Ca binding proteins in the lumen of the reticulum. A diversity of physical and chemical signals, activate the main Ca release channels, i.

Kinetics on Demand Is a Simple Mathematical Solution that Fits Recorded Caffeine-Induced Luminal SR Ca2+ Changes in Smooth Muscle Cells.

The process of Ca2+ release from sarcoplasmic reticulum (SR) comprises 4 phases in smooth muscle cells. Phase 1 is characterized by a large increase of the intracellular Ca2+ concentration ([Ca2+]i) with a minimal reduction of the free luminal SR [Ca2+] ([Ca2+]FSR). Importantly, active SR Ca2+ ATPases (SERCA pumps) are necessary for phase 1 to occur.