title: Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart.
abstract: Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart was investigated. Rat hearts were perfused with various concentrations of 3H-isoproterenol for 30 min in the absence and the presence of catechol-O-methyltransferase (COMT) inhibitor (tropolone). When COMT was intact, the accumulation of 3H-isoproterenol in both atria and ventricle after perfusion with low concentration of 3H-isoproterenol (0.01 to 1 mumol/l) was less than that of perfusing concentration; the tissue/medium ratio (T/M) of isoproterenol for artia was lower than that for ventricle. The T/M of isoproterenol after perfusion with 10 and 20 mumol/l of 3H-isoproterenol were 0.94 and 1.76 for atria and 3.25 and 2.95 for ventricle, respectively. When COMT was inhibited by tropolone, the T/M increased 6.3-9.0 folds for atria and 5.1-6.7 folds for ventricle after perfusion with 3H-isoproterenol (0.01 to 1 mumol/l). From these results, it was concluded that both atria and ventricle of the rat heart have an extraneuronal O-methylating system as reported in rat whole heart, and was suggested that there might be different capacities of extraneuronal uptake and COMT between them.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Magaribuchi
authors.forename: K
authors.initials: K
authors.lastname: Kurahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Akimoto
authors.forename: M
authors.initials: M
authors.lastname: Fujiwara
mesh_terms: D000818:Animals; D002394:Catechol O-Methyltransferase / Q000032:analysis; D006325:Heart Atria / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000378:metabolism*; D008297:Male; D008745:Methylation; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D014334:Tropolone / Q000494:pharmacology
chemical_list: D014334:Tropolone; D002394:Catechol O-Methyltransferase; D007545:Isoproterenol