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Removal of 5‐hydroxytryptamine in the pulmonary circulation of rat isolated lungs
Author(s) -
ALABASTER VALERIE A.,
BAKHLE Y. S.
Publication year - 1970
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.1476-5381.1970.tb10628.x
Subject(s) - tranylcypromine , reserpine , chemistry , iproniazid , monoamine oxidase , metaraminol , normetanephrine , phenoxybenzamine , metabolism , lung , amitriptyline , pharmacology , endocrinology , norepinephrine , medicine , biochemistry , dopamine , enzyme , urine , receptor , blood pressure
1 . Rat isolated lungs perfused via the pulmonary artery with Krebs solution removed 92% of the 5‐hydroxytryptamine (5‐HT) infused through it. This degree of removal was independent of concentration in the range from 5 to 100 g/ml. 2 . The removal of 5‐HT by the lungs was inhibited by amitriptyline and desmethylimipramine (10 −6 –10 −5 m ). 3 . The monoamine oxidase inhibitors, mebanazine and iproniazid (10 −6 –10 −5 m ), inhibited the initial removal slightly, but their main effect was to preserve the 5‐HT taken up and this 5‐HT slowly reappeared in the effluent from the lungs. Tranylcypromine (5 × 10 −7 –10 −6 m ) showed a combination of amitriptyline‐like and mebanazine‐like effects on the 5‐HT removal in rat lung. 4 . Experiments with 3 H‐5‐HT showed that although under normal conditions only 10% of the radioactivity appeared in the lung effluent as 5‐HT within the first 5 min, the rest of radioactivity administered could be recovered in the effluent over 50 min as a metabolite, probably 5‐hydroxyindoleacetic acid. 5 . The following amines were without effect on the removal of 5‐HT by rat lungs: noradrenaline (6 × 10 −7 m ), normetanephrine (5 × 10 −6 m ), metaraminol (10 −6 m ), reserpine (10 −6 –10 −5 m ) and phenoxybenzamine (10 −5 m ). 6 . We conclude that the removal of 5‐HT by rat lungs involves a process of uptake and metabolism rather than one of uptake and storage, but this process is not the catecholamine Uptake 2 . The cells involved in this process might be either capillary endothelial cells or septal cells.