[Verapamil inhibits DNA synthesis in vitro. II. Study of the MCF7 and Jurkat neoplastic cell lines].

Verapamil in cultures of mammary carcinoma MCF7 cells and Jurkat A.L.L. cells decreased the 3H-TdR incorporation. The action of Verapamil is dose-dependent. The inhibition percentage of 3H-TdR incorporation into Jurkat cells by Verapamil was lower than into MCF7 cells. No change of the mitotic inhibition was observed with higher Ca++ concentration in the medium. Modification of the Na++ and K++ content in the medium did not change action of Verapamil; this is in agreement with the independence of neoplastic cells from the culture medium. Our investigation suggests that Verapamil does not work through a block of transmembrane Ca++ flux, but rather through an intracellular interaction.