A model of calcium signaling and degranulation dynamics induced by laser irradiation in mast cells

Recent experiments show that calcium signaling and degranulation dynamics induced by low power laser irradiation in mast cells must rely on extracellular Ca2 influx.An analytical expression of Ca2 flux through TRPV4 cation channel in response to interaction of laser photon energy and extracellular Ca2 is deduced,and a model characterizing dynamics of calcium signaling and degranulation activated by laser irradiation in mast cells is established.The model indicates that the characteristics of calcium signaling and degranulation dynamics are determined by interaction between laser photon energy and Ca2 influx.Extracellular Ca2 concentration is so high that even small photon energy can activate mast cells,thus avoiding the possible injury caused by laser irradiation with shorter wavelengths.The model predicts that there exists a narrow parameter domain of photon energy and extracellular Ca2 concen-tration of which results in cytosolic Ca2 limit cycle oscillations,and shows that PKC activity is in direct proportion to the frequency of Ca2 oscillations.With the model it is found that sustained and stable maximum plateau of cytosolic Ca2 concentration can get optimal degranulation rate.Furthermore,the idea of introducing the realistic physical energy into model is applicable to modeling other physical signal transduction systems.