Platelet-derived growth factor blocks the increase in intracellular free Ca²⁺ caused by calcium ionophores and a volatile anesthetic agent in Swiss 3T3 fibroblasts without altering toxicity

Platelet-derived growth factor (PDGF) produced an almost complete block of the increase in intracellular free Ca²⁺ concentration ([Ca²⁺]_i) in Swiss 3T3 fibroblasts caused by the Ca²⁺-selective ionophores 4-bromo-A23187 and ionomycin, and by the volatile anesthetic agent halothane. The effect of PDGF was similar to the decreased [Ca²⁺]_i response to Ca²⁺-ionophores produced by phorbol 12-myristate 13-acetate, an activator of protein kinase C. There was no effect of PDGF or PMA on the acute or delayed toxicity of the Ca²⁺-ionophores to Swiss 3T3 cells, suggesting that the increase in [Ca²⁺]_i, is not the direct cause of toxicity of these agents.