Cooperative action of insulin and catecholamines on stimulation of ornithine decarboxylase activity in neonatal rat heart cells.
Toraason-M; Luken-ME; Krueger-JA
J Mol Cell Cardiol 1990 Jun; 22(6):637-644
The effect of insulin (9004108) and biogenic amines on cardiac ornithine-decarboxylase (ODC) activity was studied in-vitro. Myocytes prepared from hearts harvested from 2 to 4 day old Sprague- Dawley-rats were cultured and incubated in media containing 0 to 10% fetal bovine serum (FBS) for up to 8 hours in the presence or absence of isoproterenol (7683592) in a preliminary experiment. Induction of ODC activity was determined. Cytotoxicity was assessed by measuring leakage of lactate-dehydrogenase into the medium. Isoproterenol at concentrations of up to 10(-4) molar (M) was not cytotoxic and did not induce ODC activity in serum free medium. Isoproterenol concentrations above 10(-4)M were toxic and induced ODC activity in serum free medium. ODC was increased by FBS in a dose dependent manner. Myocytes were incubated with 10(-5)M norepinephrine (51412) or isoproterenol in medium containing 0 or 10% FBS in the presence or absence of 10(-5)M propranolol (525666). The effects on ODC activity were determined. Norepinephrine alone caused slight, nonsignificant increases in ODC activity in FBS free medium. In the presence of 10% FBS, norepinephrine and isoproterenol alone caused significant, similar increases in ODC activity, which were inhibited by propranolol. Myocytes were incubated with up to 100 micrograms per milliliter (microg/ml) insulin or 10(-5)M epinephrine (51434), norepinephrine, or isoproterenol in serum free medium in the presence or absence of 10(- 5)M propranolol. The cultures were assayed for ODC activity. Insulin at 10 and 100microg/ml significantly increased ODC activity, the increase induced by the 100microg/ml dose being only slightly greater than the increase induced by 10microg/ml. Insulin plus epinephrine, norepinephrine, or isoproterenol increased ODC activity to about the same extent as 10% FBS. These increases were inhibited by propranolol. The authors conclude that the data support the notion that beta adrenergic activation stimulates ODC activity in cultured heart cells.
NIOSH-Author; In-vitro-studies; Myocardium; Mammalian-cells; Catecholamines; Physiological-chemistry; Dose-response; Enzyme-activity; Drugs; Blood-serum
9004-10-8; 7683-59-2; 51-41-2; 525-66-6; 51-43-4
Journal of Molecular and Cellular Cardiology