Polyamine effects on [Ca2+](i) homeostasis and contractility in isolated rat ventricular cardiomyocytes

C. Ventura, C. Ferroni, F. Flamigni, C. Stefanelli, M. C. Capogrossi

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Abstract

In electrically stimulated myocytes loaded with the fluorescent Ca2+ indicator indo 1-acetoxymethyl ester, spermine induced a dose-dependent (100- 500 μM) negative inotropic effect, which was associated with a decrease in the magnitude of the cytosolic Ca2+ concentration ([Ca2+](i)) transient but not with changes in myofilament responsiveness to Ca2+. Spermidine induced a less pronounced negative inotropic effect, whereas putrescine did not modify myocyte contraction. In the unstimulated state, spermine did not alter resting [Ca2+](i). Superfusion of the cardiac myocytes with 10 mM α- difluoromethylornithine, an inhibitor of polyamine synthesis, did not modify cellular responses to isoproterenol (10-9-10-7 M). β-Adrenergic stimulation did not affect either ornithine decarboxylase activity or intracellular polyamine levels within a 10-s to 15-min period of treatment. In summary, only exogenously administered polyamines were able to influence myocyte contractility. Their negative inotropic effect resulted from changes in [Ca2+](i) homeostasis and required cellular depolarization.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume267
Issue number2 36-2
Publication statusPublished - 1994

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Keywords

  • α-difluoromethylornithine
  • β-adrenergic stimulation
  • cytosolic calcium
  • indo 1
  • ornithine decarboxylase

ASJC Scopus subject areas

  • Physiology
  • Agricultural and Biological Sciences(all)
  • Medicine(all)

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