Time-Dependent Concentration Profile of Secreted Molecules in the Intercellular Signaling

The concentration profile of secreted molecules is studied to understand characteristic properties of the intercellular signaling. Diffusion equations are solved for the concentration by assuming the rectangular, triangular and oscillatory time-dependence of the flux at the cell surface. The concentration is examined as a function of time and distance from a secreting cell by varying both the strength of an enhanced secretion rate and a secretion time. The time-dependence of the secretion rate is found to be inevitable for the concept of communication distance and characteristic time. Realistic estimations of these quantities are given for human cytokines.