title: Cooperative action of insulin and catecholamines on stimulation of ornithine decarboxylase activity in neonatal rat heart cells.
abstract: Stimulation of ornithine decarboxylase (ODC) activity was examined in cultured heart cells from neonatal rats. Fetal bovine serum had a concentration-dependent effect on ODC activity with maximum response obtained at 10% serum. ODC activity peaked 4 h after the addition of serum and returned to initial levels at 8 h. In the absence of serum, non-cytotoxic concentrations of the adrenergic agonists epinephrine, norepinephrine or isoproterenol did not stimulate ODC activity. Co-administration of serum and catecholamines at 10(-5) M induced an ODC response that was significantly greater than that induced by serum alone. A screen of various constituents of serum revealed that insulin, though relatively ineffective alone, acted cooperatively with catecholamines to produce an ODC response equivalent to that induced by 10% serum. Propranolol effectively blocked the cooperative effect of insulin on catecholamine stimulation of ODC activity, and markedly inhibited the stimulation of ODC by 10% serum. Insulin also acted cooperatively with the second-messenger analogue dibutyryl-cAMP. The calcium ionophore A23187 significantly increased ODC activity and this response was potentiated by the presence of insulin. The present findings are concordant with in vivo observations in that beta-adrenergic activation stimulates ODC activity in cultured heart cells, but it also demonstrates that the cooperative action of other factors present in serum, such as insulin, are required.
authors.affiliation: Division of Biomedical and Behavioral Science, Centers for Disease Control, National Institute for Occupational Safety and Health, Cincinnati, OH 45226.
authors.forename: M
authors.initials: M
authors.lastname: Toraason
authors.forename: M E
authors.initials: ME
authors.lastname: Luken
authors.forename: J A
authors.initials: JA
authors.lastname: Krueger
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D006332:Cardiomegaly / Q000201:enzymology; D002395:Catecholamines / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D004357:Drug Synergism; D005347:Fibroblasts / Q000201:enzymology; D006321:Heart / Q000187:drug effects; D006984:Hypertrophy; D007328:Insulin / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology / Q000633:toxicity; D009206:Myocardium / Q000166:cytology* / Q000201:enzymology; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D051381:Rats
chemical_list: D001798:Blood Proteins; D002395:Catecholamines; D007328:Insulin; D000001:Calcimycin; D000242:Cyclic AMP; D009955:Ornithine Decarboxylase; D007545:Isoproterenol