title: Inhibition of prostaglandin E1-induced elevation of cytoplasmic free calcium ion by protein kinase C-activating phorbol esters and diacylglycerol in Swiss 3T3 fibroblasts.
abstract: In quiescent cultures of Swiss 3T3 cells, prostaglandin E1 (PGE1) known to elevate cAMP increased rapidly cytoplasmic free Ca2+ concentration ([Ca2+]i) as measured with the fluorescent Ca2+ indicator quin2. The primary source of the PGE1-induced elevation of [Ca2+]i was extracellular. Pretreatment of the cells with various doses of 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent protein kinase C-activating phorbol ester, inhibited the PGE1-induced elevation of [Ca2+]i in a dose-dependent manner. Inversely, TPA enhanced slightly the PGE1-induced increase of cAMP. TPA alone did not affect the basal level of [Ca2+]i or cAMP in the absence of PGE1. The inhibitory action of TPA on the PGE1-induced elevation of [Ca2+]i was mimicked by other protein kinase C-activating agents such as phorbol 12,13-dibutyrate and 1-oleoyl-2-acetylglycerol. 4 alpha-Phorbol 12,13-didecanoate known to be inactive for protein kinase C was ineffective in this capacity. Prolonged treatment of the cells with phorbol 12,13-dibutyrate resulted in the down-regulation and disappearance of protein kinase C. In these protein kinase C-deficient cells, PGE1 still elevated [Ca2+]i to the same extent as that in the control cells, but TPA did not inhibit the PGE1-induced elevation of [Ca2+]i. These results strongly suggest that protein kinase C serves as an inhibitor for PGE1-induced Ca2+ influx in Swiss 3T3 cells.
mesh_terms: D000527:Alprostadil / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology*; D004789:Enzyme Activation; D005989:Glycerides / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D010703:Phorbol Esters / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D005989:Glycerides; D010703:Phorbol Esters; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D000527:Alprostadil; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium