Molecular and Cellular Biochemistry

, Volume 142, Issue 1, pp 25–34 | Cite as

Effect of alpha adrenergic stimulation and carnitine palmitoyl transferase I inhibition on hypertrophying adult rat cardiomyocytes in culture

  • Wieslawa Lesniak
  • Christoph Schaefer
  • Stephan Grueninger
  • Michele Chiesi


Long-term, serum supplemented cultures of rat adult ventriculocytes were utilized to study the trophic effects of the α-agonist phenylephrine and of the carnitine palmitoyltransferase I inhibitor etomoxir. Cell protein and the rate of incorporation of phenylalanine were measured, corrected for cellular DNA content and utilized as an index for hypertrophy and of anabolic acitivity of the cells, respectively. The mRNA level of ANF was utilized as an index for the pathological phenotypic change (i.e., switch to fetal gene program), and that of the Na-channel — a constantly expressed gene in normal and hypertrophic cardiomyocytes — served as an internal control. Both mRNAs were quantified at various stages in culture by competitive reverse transcriptase PCR.

The size of control myocytes steadily increased for over 3 weeks. The cells were completely redifferentiated and reached a maximum of anabolic activity 2 weeks after plating. Secretion and mRNA levels of ANF were increased severalfold after 7–8 days. Addition of 10 μM phenylephrine considerably speeded up cell growth. Maximum anabolic activity and complete redifferentiation were reached already after 1 week. Levels of mRNA and of ANF release increased 30–40 fold. Interestingly, induction of ANF gene transcription lagged behind the redifferentiation of the cells.

Ten μM etomoxir inhibited the oxidation of palmitic acid and stimulated that of exogenous glucose by adult cardiomyocytes. In spite of its clear effect on fuel utilization, etomoxir had no direct hypertrophic effect on the myocytes in culture and did not inhibit the stimulatory action of α-agonists. Reactivation of the fetal gene program, as visualized by ANF production, was not reversed by etomoxir.

Key words

heart ANF phenylephrine etomoxir metabolism 


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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Wieslawa Lesniak
    • 1
  • Christoph Schaefer
    • 1
  • Stephan Grueninger
    • 1
  • Michele Chiesi
    • 1
  1. 1.Pharmaceuticals DivisionCiba-Geigy LtdBasleSwitzerland

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