Calcium and calcium slow channel antagonists on cyclic nucleotide levels in the isolated rat heart

Alan Daugherty, Brian Woodward

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


An investigation has been carried out into the effects of extracellular calcium on cyclic nucleotide levels in rat ventricle. Increasing extracellular calcium, over the range which directly affected contractility, produced a concentration related increase in the level of cyclic AMP. Positive correlations were found between extracellular calcium and cyclic AMP; and between cyclic AMP and isometrically developed tension. No reciprocal relationships were found for cyclic GMP over the same calcium concentration range. Increasing extracellular calcium above the maximal inotropic concentration did not produce a further increase in cyclic AMP, although increases in cyclic GMP were noted. Calcium slow channel antagonists, nifedipine and manganese both depressed developed tension at the concentrations used, but this effect was not associated with any significant change in cyclic nucleotide levels. Verapamil depressed developed tension and cyclic AMP levels but the effect on cyclic AMP was not concentration related. No calcium slow channel antagonist significantly affected cyclic GMP levels. In electrically paced hearts, increasing rate of stimulation depressed developed tension but had no significant effect on cyclic AMP.

Original languageEnglish
Pages (from-to)843-854
Number of pages12
JournalJournal of Molecular and Cellular Cardiology
Issue number9
StatePublished - Sep 1981

Bibliographical note

Funding Information:
We thank Abbott Laboratories Ltd, for verapamil, Bayer Pharmaceuticals for nifedipine, and Dr D. M. Yellon (Myocardial Metabolism Laboratory, St Thomas’ Hospital) for cyclic AMP binding protein. This work is supported by the British Heart Foundation and the University of Bath Research Fund.


  • Ca
  • Ca slow channel antagonists
  • Cyclic AMP
  • Cyclic GMP
  • Developed tension
  • Heart rate
  • Rat ventricle

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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