title: Calcium modulation of phorbol ester-induced alterations in murine macrophage morphology.
abstract: The phorbol ester tumor promoter phorbol-12-myristate-13-acetate (PMA) induced mouse resident peritoneal macrophage spreading in an in vitro system in a time- and dose-dependent manner; this process was modified by agents which alter intracellular calcium metabolism. After a 35-min incubation with PMA, 50% of the macrophages were spread (as classified by at least a 2-fold increase in cell surface area). Also at 35 min, the median effective concentration for PMA induction of spreading was 1.6 ng/ml. The intracellular calcium antagonist 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate inhibited PMA-induced cell spreading with a one-half maximal inhibitory concentration of 8.0 microM. The calcium ionophore A23187 enhanced PMA-induced spreading by 30% at 0.1 to 10 nM. The histological dye ruthenium red, which purportedly increases intracellular calcium by displacing membrane-bound calcium stores, enhanced PMA-induced spreading up to 75% at 1.0 pM. The cationic chelator ethyleneglycolbis(beta-aminoethylether)-N,N-tetraacetic acid (1.8 and 3.6 mM) had no effect on PMA-induced spreading. Thus, PMA-induced spreading was independent of extracellular calcium but was modulated by agents altering intracellular calcium metabolism. Microfilament formation, a proposed mechanism of cell spreading, also depends on intracellular calcium availability. The microfilament inhibitor cytochalasin B inhibited PMA-induced spreading with a one-half maximal inhibitory concentration of 1 microM. Future experiments should investigate the hypothesis that calcium availability to the cytoskeletal elements regulates the morphological effects of PMA on macrophages.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002448:Cell Adhesion; D002452:Cell Count; D003571:Cytochalasin B / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D010704:Phorbols / Q000494:pharmacology*; D012430:Ruthenium Red / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D010704:Phorbols; D012430:Ruthenium Red; D000001:Calcimycin; D003571:Cytochalasin B; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium