Differential regulation of g protein expression in rat hearts
exposed to chronic hypoxia.
Kacimi, Rachid, Jean-Marie Moalic, Almas Aldashev, Dorothy E. Vatner,
Jean-Paul Richalet, and Bertrand Crozatier.
Institut National de la Sant[umlaut]a et de la Recherche
M[umlaut]adicale Unit[umlaut]a INSERM U400 94010 Cr[umlaut]ateil
cedex, [alpha]Unit[umlaut]a INSERM U127 75010 Paris, France and
[tilde]nHarvard Medical School N.E.R.P.R.C. Southboro MA, USA
APStracts 2:0278H, 1995.
Chronic hypoxia (HX) impairs adrenergic responsiveness. A modulation
of Gs and/or Gi protein alpha subunits may be associated with the
down-regulation of the beta-adrenergic receptors previously found in
HX. G protein gene expression and protein level and function in rat
hearts exposed to a 30 day hypobaric HX were compared to control (CL)
rat hearts. No change was observed in Gas mRNA levels in both right
ventricles (RV) and left ventricles (LV). In RV, mRNA levels of Gai2
increased by 40% (p<0.05), but not in LV. In both LV and RV, HX
did not modify Gai2 and Gas protein amounts but significantly
decreased functional activity of Gas. In conclusion, gene expression,
protein levels of Gas and Gai2 and activity of Gas do not change in
parallel fashion with HX. In HX RV, although the mRNA level of Gai2
is increased, protein level is unchanged. One potential mechanism of
desensitization to catecholamines in HX appears to involve a
decreased functional activity of Gas in spite of normal mRNA and
protein levels.
Received 15 August 1994; accepted in final form 12 June 1995.
APS Manuscript Number H734-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.