Inhibition by isoptin (a calcium antagonist) of the mitogenic stimulation of lymphocytes prior to the S-phase.

Isoptin (alpha-isopropyl-alpha-(N-methyl-N-homoveratryl)-gamma-amino-propyl-3,4-dimethoxyphenylacetonitril-hydrochloride)--a calcium antagonist--inhibits mitogenic stimulation of lymphocytes. Isoptin acts prior to the S-phase of the cehl cycle but does not prevent the early events involved in triggering of cell mitosis. The drug seems to be a good tool for studying the relevance of the 'early events' assumed to be involved in lymphocyte stimulation.