Differential regulation of G protein expression in rat hearts exposed to chronic hypoxia

R. Kacimi, J. M. Moalic, A. Aldashev, D. E. Vatner, J. P. Richalet, B. Crozatier

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45 Scopus citations


Chronic hypoxia impairs adrenergic responsiveness. A modulation of G(s) and/or G(i) protein α-subunits may be associated with the downregulation of the β-adrenergic receptors previously found in chronic hypoxia. G protein gene expression and protein level and function in rat hearts exposed to a 30- day hypobaric chronic hypoxia were compared with control rat hearts. No change was observed in Gα(s) mRNA levels in either right or left ventricles. In right ventricles, mRNA levels of Gα(i-2) increased by 40% (P < 0.05), but not in left ventricles. In both left and right ventricles, chronic hypoxia did not modify Gα(i-2) and Gα, protein amounts, but significantly decreased functional activity of Gα(s). In conclusion, gene expression, protein levels of Gα(s) and Gα(i-2), and activity of Gα(s) do not change in parallel fashion with chronic hypoxia. In chronic hypoxic right ventricles, although the mRNA level of Gα(i-2) is increased, the protein level is unchanged. One potential mechanism of desensitization to catecholamines in chronic hypoxia appears to involve a decreased functional activity of Gα(s) in spite of normal mRNA and protein levels.

Original languageEnglish (US)
Pages (from-to)H1865-H1873
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number6 38-6
StatePublished - 1995

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


  • adrenergic signal transduction
  • messenger ribonucleic acid
  • myocardium

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