QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by AUGUSTINE, G. J. Articles by FETTERER, R. H. Search for Related Content PubMed Articles by AUGUSTINE, G. J. Articles by FETTERER, R. H.

Journal of Experimental Biology 118,53-69 (1985)
Published by Company of Biologists 1985

Neurohormonal Modulation of the Limulus Heart: Amine Actions on Cardiac Ganglion Neurones

GEORGE J. AUGUSTINE ¹ and RAYMOND H. FETTERER ²

¹ Department of Biological Sciences, University of Southern California Los Angeles, CA 90089-0371, U.S.A., Marine Biological Laboratory, Woods Hole, MA and Department of Zoology, University of Maryland College Park, MD
² Department of Biological Sciences, University of Southern California Los Angeles, CA 90089-0371, U.S.A., Marine Biological Laboratory, Woods Hole, MA and Department of Zoology, University of Maryland College Park, MD; U.S. Department of Agriculture, Agricultural Research Service, Animal Parasitology Institute, Beltsville, MD, U.S.A.

Octopamine (OCT), dopamine (DA), epinephrine (EPI) and norepinephrine (NE) are endogenous excitors of the Limulus heart. The cellular sites of action of these amines were investigated by recording responses of neurones in the cardiac ganglion. There was an increase in spike frequency in pacemaker neurones, accompanied by a depolarization and an increase in the rate of repolarization of the ‘pacemaker potential’. DA also produced a transient decrease in pacemaker spike frequency which preceded its excitatory effect. All four amines produced slow, dosedependent increases in the frequency of bursting activity in cardiac ganglion follower neurones. These increases were blocked by the antagonist phentolamine. DA and NE also produced transient decreases in burst rate which were blocked by the antagonist metergoline. Local application of DA on to pacemaker cells increased follower cell burst frequency, while similar applications on to follower cells did not affect burst frequency. This indicates that DA acts directly upon pacemaker neurones to increase cardiac ganglion burst activity. In addition to their pacemaker-mediated effects, the amines also had direct effects upon follower cells. These effects were examined after eliminating follower cell bursting activity with cobalt ions. OCT and, to a smaller extent, EPI, depolarized follower cells. DA and, occasionally, NE hyperpolarized follower cells. The hyperpolarizing DA response was due to a conductance increase and was blocked by metergoline and ergonovine.

Key words: Limulus, neurohormones, cardiac ganglion, amines, bursting neurones

Accepted on February 28, 1985

This article has been cited by other articles:

				N. D. Cruz-Bermudez and E. Marder Multiple modulators act on the cardiac ganglion of the crab, Cancer borealis J. Exp. Biol., August 15, 2007; 210(16): 2873 - 2884. [Abstract] [Full Text] [PDF]