Accumulation of 3H-adrenaline by rabbit aorta.
The accumulation of (-)-3H-adrenaline (3H-A) by rabbit isolated aorta was studied. In all experiments, monoamine oxidase and catechol-O-methyltransferase were inhibited by treatment with pargyline and 3',4'-dihydroxy-2-methyl-propiophenone (U-0521), respectively. The relationship between the accumulation of 3H derived from 3H-A (10(-8) M) and the duration of incubation (0-3 h) was linear. The 3H-accumulation after 3 h incubation was 22.5 ml X g-1. In reserpine-treated tissue, the 3H-accumulation levelled off after 30 min and was 8.5 ml X g-1 after 3 h. The concentration of 3H-A or (-)-3H-noradrenaline (3H-NA) and the 3H-accumulation (ml X g-1) were inversely related. At 10(-8) M, the 1-hour accumulation of 3H derived from 3H-A and 3H-NA was 7.8 and 15.2 ml X g-1, respectively. With increasing concentrations (3 X 10(-8)-10(-4) M), the accumulation values approached each other. At 10(-4) M, the accumulation was 2.3 and 2.8 ml X g-1 for 3H-A and 3H-NA, respectively. The accumulation of 3H derived from 3H-A (10(-8)-10(-4) M) by reserpine-treated tissue also showed an inverse relationship with concentration: 5.4 ml X g-1 (10(-8) M) and 2.6 ml X g-1 (10(-4) M). The accumulation of 3H derived from 3H-A (10(-8) M; 1 h) was dependent on the bath temperature (1-37 degrees C). The accumulation increased continuously from 1.1 ml X g-1 (1 degree C) to 11.1 ml X g-1 (37 degrees C). Storage of tissue (0-5 days in salt solution without equilibration with 95% O2/5% CO2; 4 degrees C) did not affect the accumulation of 3H derived from 3H-A (10(-8) M; 1 h). Thereafter (7-14 days), the accumulation decreased. The inhibitory potency (IC50;-log M) of desimipramine, cocaine, (-)-propranolol, (-)-isoprenaline, and (+/-)-normetanephrine on accumulation of 3H derived from 3H-A (10(-8) M; 1 h) was found to be 8.26; 6.50; 5.48, 4.88, and 4.02, respectively. The maximal degree of inhibition was almost the same for these drugs, while that of clonidine and corticosterone was 50 and 20%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging / Q000378:metabolism*; D065098:Catechol O-Methyltransferase Inhibitors; D003000:Clonidine / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D004837:Epinephrine / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism; D066298:In Vitro Techniques; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D009647:Normetanephrine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D011877:Radionuclide Imaging; D014316:Tritium
D065098:Catechol O-Methyltransferase Inhibitors; D007461:Iodoacetates; D008996:Monoamine Oxidase Inhibitors; D009647:Normetanephrine; D014316:Tritium; D010042:Ouabain; D011433:Propranolol; D003042:Cocaine; D003000:Clonidine; D003891:Desipramine; D019807:Iodoacetic Acid; D009638:Norepinephrine; D004837:Epinephrine