Abstract
Six tricyclic compounds, in concentrations causing no nonspecific depression of spontaneous function inhibited the chronotropic effect of histamine on isolated rabbit atria. Common to these substances was an aliphatic side chain linked to flue tricyclic structure through the central ring. Inhibitory action was slow in onset (for promethazine, t½ ≈ 25 minutes, under certain experimental conditions) and was not reversed by washing during the period of an experiment. Five other tricyclic compounds having piperidine or piperazine side chains did not inhibit the chronotropic action of histamine when applied in concentrations having no appreciable nonspecific depressant effect. In concentrations greater than 5 x 10-6 M, all 11 compounds produced nonspecific depression of spontaneous rate.
Footnotes
- Received February 16, 1974.
- Accepted July 9, 1974.
- © 1974 by The Williams & Wilkins Co.
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