title: Mitogen and co-mitogen stimulation of lymphocytes inhibited by three Ca++ antagonists.
abstract: The Ca++ requirement for in vitro lymphocyte stimulation by lectins is well known and can be demonstrated by the use of Ca++ chelators. In this study, three Ca++ antagonists were examined for their effects on lymphocyte proliferation. [3H]-thymidine incorporation was employed to measure DNA synthesis in several systems. Stimulation and proliferation were achieved by the addition of one of the following: the mitogenic lectin concanavalin A (ConA); the combination of two co-mitogens, the calcium ionophore A23187 and the phorbol ester, 12-0-tetradecanoylphorbol-13-acetate (TPA), neither of which is mitogenic alone; or the non-mitogenic lectin, wheat germ agglutinin (WGA) with TPA. These mitogenic systems were tested for their sensitivity to the Ca++ channel blockers verapamil and nicardipine and the intracellular Ca++ antagonist TMB-8. We found that the ConA and WGA plus TPA treated cells were inhibited approximately 50% by 10 microM verapamil, nicardipine or TMB-8. The stimulation caused by A23187 and TPA was only inhibited by TMB-8 and nicardipine. The inhibitory effects caused by the Ca++ antagonists could not be reversed by the addition of exogenous Ca++ (0.1-1.5 mM), but were reversed by repeated washings in antagonist free media. Using TMB-8 we saw an apparent intracellular Ca++ dependence throughout the G1 phase. Previous studies using Ca++ chelators or Ca++ antagonists suggested an endpoint at about halfway through this period.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D004357:Drug Synergism; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000166:cytology*; D008934:Mitogens / Q000494:pharmacology*; D009529:Nicardipine; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology; D014909:Wheat Germ Agglutinins
chemical_list: D002121:Calcium Channel Blockers; D037102:Lectins; D008934:Mitogens; D014909:Wheat Germ Agglutinins; D003208:Concanavalin A; D000001:Calcimycin; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D014700:Verapamil; D009529:Nicardipine; D009543:Nifedipine; D013755:Tetradecanoylphorbol Acetate