Exogenous ATP causes the contraction of intact fibroblasts in vitro

The contraction of intact fibroblasts was investigated in vitro. The addition of ATP to the cells lead to a rapid, reversible reduction of cell area, which appeared to be a contraction. The change of cell area was measured using image analysis. ATP (15 mM) elicited the maximal contraction, with a 50% reduction in area achieved within 90 s. Adenosine was a partial agonist for the contraction. The contraction was dependent on control of the environmental calcium; cells in a calcium- and magnesium-free environment underwent spontaneous contraction. Replenishing the calcium and magnesium lead to stability of the cells. Since fibroblast contraction is involved in wound healing at many sites in the body, this system provides a physiological model for the direct investigation of fibroblasts with intact cell membranes, and allows for the testing of drugs which may influence wound healing in vivo.