Mitogens and melittin stimulate an increase in intracellular free calcium concentration in human fibroblasts

Intracellular free Ca+2 concentration was measured in cultured human fibroblasts (HSWP) utilizing the Ca+2-sensitive fluorescent probe quin2. The addition of peptide growth factors to serum-deprived HSWP cells induced an immediate rise in intracellular Ca+2 concentration. This mitogen-induced rise in Ca+2 concentration could be blocked by the addition of the intracellular Ca+2 antagonist TMB-8. Addition of the phospholipase activator, melittin, to cells in the absence of growth factors also caused a dramatic rise in intracellular Ca+2 concentration which was blocked by TMB-8.