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Effects of 5-Hydroxytryptamine on Action Potentials and on Contractile Force in the Ventricle of Dolabella Auricularia
1 Department of Zoology, University of Rhode Island, Kingston, Rhode Island 02881, U.S.A., and Kewalo Marine Laboratory, Pacific Biomedical Research Center, University of Hawaii, 41 Ahui St., Honolulu, Hawaii 96813, U.S.A.
1. Concentrations of 5-hydroxytryptamine from 10-8 to 10-5 M had the effect of starting quiescent ventricles, with a slow slight depolarization followed by the onset of beating, with hyperpolarization between beats.
2. Concentrations of 5-hydroxytryptamine from 10-7 to 10-3 M had the effect of prolonging the cardiac action potential and increasing force. Over the entire range, an increase in concentration led to an increase in the duration and amplitude of the plateau phase of the action potential, and an increase in force of contraction.
Submitted on April 2, 1974