The effects of theophylline and 3-isobutyl-1-methylxanthine on the contractility, cyclic AMP content and phosphodiesterase activity of the M. Mercenaria ventricle

Stephen D. Hess, Paul D. Reiss, William J. Higgins

Research output: Contribution to journalArticle

3 Scopus citations


1. Theophylline and 3-isobutyl-1-methylxanthine (IBMX) are relatively poor inhibitors of cyclic AMP phosphodiesterase from the ventricles of the bivalve Mercenaria mercenaria (I50 = 4.5 × 10-3 and 2 × 10-3 M, respectively). 2. At doses ≤10-4 M, these agents have no effect on myocardial contractility or cyclic AMP content. 3. However, IBMX (10-4 M) does potentiate the cardio-excitatory actions of a subthreshold of 5-hydroxytryptamine.

Original languageEnglish (US)
Pages (from-to)13-18
Number of pages6
JournalComparative Biochemistry and Physiology. Part C, Comparative
Issue number1
StatePublished - 1981


ASJC Scopus subject areas

  • Immunology
  • Pharmacology

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