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THE UPTAKE KINETICS AND METABOLISM OF EXTRANEURONAL NORADRENALINE IN GUINEA‐PIG TRACHEA AS STUDIED WITH QUANTITATIVE FLUORESCENCE MICROPHOTOMETRY
Author(s) -
O'DONNELL STELLA R.,
SAAR NILI
Publication year - 1978
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1978.tb08451.x
Subject(s) - nialamide , monoamine oxidase , guinea pig , monoamine oxidase inhibitor , tropolone , fluorescence , metabolism , catechol , biology , chemistry , catechol o methyl transferase , endocrinology , biochemistry , medicine , biophysics , enzyme , allele , genetics , gene , physics , quantum mechanics
1 Extraneuronal uptake of noradrenaline and α‐methylnoradrenaline into single cells of guinea‐pig tracheal smooth muscle have been studied by means of quantitative fluorescence microphotometry. 2 Fluorescence brightness due to accumulation of α‐methylnoradrenaline was dose‐dependent and was increased by the catechol‐ O ‐methyltransferase inhibitor drugs, tropolone or β‐thujaplicin (200 μM) but not by 3,4‐dimethoxy‐5‐hydroxybenzoic acid (200 μM). 3 Fluorescence brightness due to accumulation of noradrenaline was increased if animals were pretreated with the monoamine oxidase inhibitor drug, nialamide. 4 The study suggests that metabolism of amines by catechol‐ O ‐methyltransferase and monoamine oxidase can occur subsequent to extraneuronal uptake in guinea‐pig tracheal smooth muscle. 5 The uptake of noradrenaline into tracheal smooth muscle was concentration‐dependent, saturable, and had a K m of 156 μM.