Figure 2.
Response to ATP of fibroblast cells in a two-dimensional culture on PA gels. (a) When a fibroblast cell culture (i) is excited by ATP, only a fraction of cells respond (ii). Out of those that respond, a sub-fraction of cells oscillate (iii). (b) Typical calcium response curves for single cells on various PA substrates. Cells on a stiff substrate exhibit a strong initial response to ATP followed by decay in calcium intensity, while cells on a soft substrate show more persistent oscillations. Inset: average damping coefficient ς varies with substrate Young's modulus. A stiffer substrate produces a faster Ca2+ decay following ATP excitation. (c) The percentage of responsive, oscillating cells in a culture depends on the ATP concentration and the elasticity of the gel to which the cells adhere. Values are the average of three experiments and error bars are standard errors of the mean (*p ≤ 0.05, **p ≤ 0.01). (Online version in colour.)