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ROLE OF SYMPATHETIC NERVES IN THE METABOLISM OF EXOGENOUS NORADRENALINE IN RABBIT GINGIVAL TISSUE AND EAR ARTERY
Author(s) -
Parker I,
Parker DAS,
Lande IS,
Thompson JA,
Proctor C,
Marino V
Publication year - 1986
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1986.55
Subject(s) - deamination , normetanephrine , artery , chemistry , endocrinology , human ear , medicine , denervation , metabolism , sympathectomy , norepinephrine , catecholamine , dopamine , biochemistry , biology , enzyme , physics , acoustics
Summary Uptake and metabolism of 3 H‐noradrenaline 0·18 μmol/l was examined in rabbit gingival slices and ear artery segments. The tissues were ineubated with the 3 H‐amine for 30 min. The artery accumulated approximately ten times more of the 3 H‐amine and generated four times more 3 H‐metabolites than the gingiva. In both tissues, chronic sympathetic denervation resulted in marked decreases in 3 H‐noradrenaline accumulation and deamination., An inhibitor of sympathetic neuronal uptake, cocaine 30 μmol/l, strongly inhibited the firmly‐bound component of 3 H‐noradrenaline accumulation by the tissues and strongly decreased the accumulation of deaminated metabolites in the incubating medium. It is concluded that the sympathetic nerve terminals play an important role in the accumulation and deamination of noradrenaline in the gingiva and in the artery. Chronic sympathetic denervation resulted in increased 3 H‐normetanephrine (NMN) formation by the gingiva and the artery, indicating that in both tissues the noradrenaline was O‐methylated at sites extraneuronal to the sympathetic nerves. Differences between the effects of cocaine in the gingiva and artery, with respect to 3 H‐NMN accumulation in the incubating medium, are interpreted as evidence that in the gingiva, but not in the artery, cocaine inhibits extraneuronal O‐methyiation, as well as neuronal uptake, of noradrenaline.