FMRFamide increases the adenylate cyclase activity and cyclic AMP level of molluscan heart

William Joseph Higgins, David A. Price, Michael J. Greenberg

Research output: Contribution to journalArticle

30 Scopus citations


FMRFamide (phenylalanyl-methionyl-arginyl-phenylalanine amide) is a cardioexcitatory peptide recently isolated and identified in molluscan ganglia. Both FMRFamide and 5-hydroxytryptamine (5HT), the cardioexcitatory neurotransmitter in molluscs, were tested on the ventricle of the bivalve Mercenaria mercenaria. Both agents increased myocardial contractility, the intracellular cyclic AMP concentration of intact hearts and the adenylate cyclase activity of a myocardial membrane fraction. FMRFamide was 5-10 times more potent than 5HT. All of the effects of 5HT, and none of those of FMRFamide, were blocked by methysergide, a specific 5HT antagonist.

Original languageEnglish (US)
Pages (from-to)425-430
Number of pages6
JournalEuropean Journal of Pharmacology
Issue number4
Publication statusPublished - Apr 15 1978



  • 5-Hydroxytryptamine
  • Adenylate cyclase
  • Cyclic AMP in muscle
  • FMRFamide
  • Methysergide
  • Molluscan heart

ASJC Scopus subject areas

  • Pharmacology

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