Showing papers on "Catechol-O-methyl transferase published in 1986"

Effect of Antihypertensive Drugs on Catechol-O-Methyltransferase and Monoamine Oxidase Activity in Human Term Placental Explants

Abstract: The effects of therapeutic concentrations of antihypertensive drugs on catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) activities in term placental explants were studied The enzyme activities were measured in tissue fractions using radioenzymatic techniques At 6 h the incubation COMT activity increased significantly following exposure to verapamil and hydralazine, while exposure to alpha methyldopa caused a significant suppression of the enzyme At 24 h exposure to hydralazine significantly suppressed the COMT activity By 6 h the MAO activity was significantly suppressed by verapamil MgSO4 and propranolol had no effect on the activities of COMT and MAO at 6 and 24 h These results suggest that COMT and MAO activities in the placenta can be modulated by antihypertensive drugs and, therefore, these drugs might affect local catechol metabolism

Isolation of the low-molecular-mass form of catechol O-methyltransferase from rat liver and immunocytochemical localization of the enzyme in the glycogen compartment.

Abstract: The low-molecular-mass form of two distinct catechol O-methyltransferase activities (S-adenosyl-L-methionine: catechol O-methyltransferase, COMT, EC 2.1.1.6) has been purified to homogeneity from rat liver using 40-70% ammonium sulfate precipitation, gel filtration on Sephadex G-100, adsorption on hydroxyapatite C and ion-exchange chromatography on DEAE-Sepharose CL-6B. The relative molecular mass Mr, determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis is 22 400 +/- 500. Irradiation of the enzyme in the presence of 8-azido-[methyl-3H]AdoMet results in the specific labeling of the catalytic site of the enzyme. Photolabeling was successful with crude COMT preparations and with the isolated enzyme. Immunocytochemical studies present new information about the localization of the low-molecular-mass form in the liver parenchyma. Subcellularly COMT immunoreactivity could be attributed exclusively to the compartment with glycogen granules. Nucleus, mitochondria and endoplasmic reticulum showed no immunostaining.

β-Phenylethylamine effect on brain and blood catechol-O-methyltransferase activity☆☆☆

Abstract: A significant decrease in catechol-o-methyltransferase (COMT) activity has been found in the striatum (77% of control) and hippocampus (63% of control) of gerbils treated with daily injections of beta-phenylethylamine (50 mg/kg) for 10 days. This treatment group also exhibited increased (204% above control) COMT activity in a lysed red blood cell preparation. There were no changes in COMT activity in groups receiving 10 mg/kg beta-phenylethylamine or haloperidol (0.5 mg/kg). In vitro beta-phenylethylamine has no demonstrable effect on COMT activity.