[The research of mathematical model for inositol-1,4,5-triphosphate-induced Ca2+ oscillations]

This article mainly illustrates the model for agonist-stimulated Ca2+ oscillations that involves two roles for cytosolic Ca2+: (a) inositol-1.4.5-triphosphate(IP3) inhibits Ca2+ release from the endoplasmic reticulum (ER); (b) IP3 acts on phosphate C, via a Gq protein related mechanism and hence stimulates Ca2+ release from ER. The model assumes that the ER IP3 receptor is a tetramer of independent subunit that can bind both Ca2+ and IP3. The reason for inhibition of Ca2+ oscillations is that IP3-receptor/Ca(2+)-channel slowly comes back to the beginning stable state. The key parameter for Ca2+ oscillations is the ratio of Maximum Ca2+ dependent IP3 input rate (v6) to IP3 decay rate constant (v7): I when v6/v7 < 0.28, no oscillation could be found; II when 0.28 < v6/v7 < 0.572, oscillation starts; III when v6/v7 > 0.572, Ca2+ ceases and arrives at a stable state quickly.