Advertisement

Acta Biologica Hungarica

, Volume 55, Issue 1–4, pp 335–341 | Cite as

RFamide Neuropeptide Actions on the Molluscan Heart

  • A. MoulisEmail author
Open Access
Article

Abstract

FMRFamide and the related tetrapeptide FLRFamide are highly excitatory in molluscan non-cardiac smooth muscle. They are also exceptionally excitatory in the atrium and internally perfused ventricle of Busycon canaliculatum. These two peptides, usually thought of as classic molluscan cardio-acceleratory agents are in fact simply two members of a large and ever growing superfamily, the RFamide family, whose phylogenetic distribution has been so elegantly mapped by Walker [16]. Members of this family, often with extended peptide chains (e.g. penta, hepta and decapeptides), stretch in their known distribution from the cnidaria to the chordates. The effects of some of the members of this superfamily (FMRFamide, FLRFamide, YMRFamide, TNRNFLRFamide, SDPFLRFamide, LMS) were examined. The neuropeptides were found to be very potent at very low concentrations (10–9 M) in the ventricle of both Buccinum and Busycon. Other neuropeptides (HFMRdFamide, SCPb, NLERFamide and pEGRFamide) were found to be without any effect. The Ca2+ dependency of these neuropeptides was also tested. The peptides appear to induce contraction of the ventricles by release of Ca2+ from internal pools. The neuropeptides appear to stimulate contraction in these cardiac muscles through a completely different pathway to Serotonin (the main excitatory neurotransmitter for the cardiac muscle). When the peptides were applied together with Serotonin an additive effect was observed clearly indicating the release of Ca2+ through different pathways. The nature of the RFamide receptor was also tested. It appears that the RFamide neuropeptides mobilize the 2nd messenger IP3 (Inositol trisphosphate), since the IP3 blocker Neomycin Sulphate inhibited the response of the neuropeptides.

Keywords

Buccinum undatum Busycon canaliculatum Ca2+ dependency RFamide neuropeptides serotonin 

References 39

  1. 1.
    Brooks, D. D. (1982) Membrane currents associated with contraction in molluscan visceral muscle. PhD Thesis, University of Lancaster, U.K.Google Scholar
  2. 2.
    Greenberg, M. J., Price, D. A. (1979) FMRFamide, a cardioexcitatory neuropeptide of molluscs. An agent in search of a mission. Am. Zool. 19, 163–174.CrossRefGoogle Scholar
  3. 3.
    Cottrell, G. A., Davies, N. W. (1987) Multiple receptor sites for a molluscan peptide (FMRFamide) and related peptides of Helix. J. Physiol. (Lond.) 382, 51–68.CrossRefGoogle Scholar
  4. 4.
    Ellis, A. M. (1998) The physiology, structure and pharmacology of the heart of Buccinum undatum. Ph.D. Thesis, University of Lancaster.Google Scholar
  5. 5.
    Hill, R. B., Langton, P. D. (1988) Use of a sucrose gap apparatus to record electrical responses of gastropod radular protractor muscle to FMRFamide. Comp. Biochem. Physiol. C 90, 113–122.CrossRefGoogle Scholar
  6. 6.
    Huddart, H., Nelson, I. D., Brooks, D. D., Hill, R. B. (1992) The calcium dependency of electrical and mechanical responses of the odontophore protractor muscle of Busycon canaliculatum. A sucrose gap study of calcium antagonist action. Comp. Biochem. Physiol. A 102, 299–305.CrossRefGoogle Scholar
  7. 7.
    Huddart, H., Hill, R. B. (1996) Electrical and mechanical characteristics of the atrium of the whelk Busycon canaliculatum. Gen. Pharmacol. 27, 1247–1254.CrossRefGoogle Scholar
  8. 8.
    Huddart, H., Hill, R. B. (1996) Modulatory mechanisms in the isolated internally perfused ventricle of the whelk Busycon canaliculatum. Gen. Pharmacol. 27, 809–818.CrossRefGoogle Scholar
  9. 9.
    Huddart, H., Nelson, I. D., Brooks, D. D., Hill, R. B. (1992) Electrical and mechanical responses of the odontophore protractor muscle of Busycon canaliculatum: a sucrose-gap voltage clamp study. Comp. Biochem. Physiol1. 102C, 149–158.Google Scholar
  10. 10.
    Hunt, S. (1981) Molluscan visceral muscle fine structure. General structure and sarcolemmal organization in the smooth muscle of the intestinal wall of Buccinum undatum L. Tissue & Cell 13, 283–297.CrossRefGoogle Scholar
  11. 11.
    Nelson, I. D., Huddart, H. (1994) Neuromodulation in molluscan smooth muscle: the action of 5-HT, FMRFamide and purine compounds. Gen. Pharmacol. 25, 539–552.CrossRefGoogle Scholar
  12. 12.
    Price, D. A. (1986) Evolution of a molluscan cardioregulatory neuropeptide. Am. Zool. 26, 1007–1015.CrossRefGoogle Scholar
  13. 13.
    Price, D. A., Greenberg, M. J. (1980) Pharmacology of the molluscan cardioexcitatory neuropeptide FMRFamide. Gen. Pharmacol. 11, 237–241.CrossRefGoogle Scholar
  14. 14.
    Smith, P. J. S., Hill, R. B. (1986) Cardiac performance in response to loading pressures and perfusion with 5-hydroxytryptamine in the isolated heart of Busycon canaliculatum (Gastropoda, Prosobranchia). J Exp. Biol. 123, 243–253.Google Scholar
  15. 15.
    Smith, P. J. S., Hill, R. B. (1987) Modulation of output from an isolated gastropod heart: effects of acetylcholine and FMRFamide. J. Exp. Biol. 127, 105–120.Google Scholar
  16. 16.
    Walker, R. J. (1992) Neuroactive peptides with an RFamide or Famide carboxyl terminal. Comp. Biochem. Physiol. 102C, 213–222.Google Scholar

Copyright information

© Akadémiai Kiadó, Budapest 2004

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  1. 1.Department of Biological SciencesLancaster UniversityLancasterUK

Personalised recommendations