EFFECTS OF STRUCTURAL MODIFICATIONS OF CATECHOLAMINES ON RENAL TUBULAR TRANSPORT IN THE CHICKEN

¹ Department of Pharmacology, School of Medicine, State University of New York, Buffalo, New York

The renal tubular transports of radioactively labeled ethylamine, phenylethylamine, tyramine, dopamine, octopamine, 3, 4-dimethoxyphenylethylamine, norepinephrine, epinephrine and isoproterenol were studied in unanesthetized chickens by use of the Sperber technique. The efficiency of transport of these amines was increased by the presence of the phenyl ring and ring hydroxyl groups. The transports of phenylethlyamine, tyramine and dopamine were inhibited by the organic base transport inhibitor, cyanine 863. Epinephrine transport was inhibited by the organic base transport inhibitor, quinine, as well as by cyanine 863. Norepinephrine transport has previously been reported to be inhibited by organic base transport inhibitors. These results suggest that all the analogs of the catecholamines studied are transported by the organic base transport system. The transports of dopamine, tyramine, phenylethylamine and 3,4-dimethoxyphenylethylamine were inhibited by probenecid. Previously epinephrine and norepinephrine transports were found to be inhibited by probenecid, and it was tentatively concluded that these occupied the organic acid transport system. However, probenecid inhibition of phenylethylamine and 3,4-dimethoxyphenylethylamine transports suggests that this action by probenecid is not specific for organic acid transports.

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