title: Effect of training on beta1 beta2 beta3 adrenergic and M2 muscarinic receptors in rat heart.
abstract: OBJECTIVE
  Physical training is known to alter several cardiovascular parameters. These adaptations are for a great part linked to an alteration of the myocardial responses to its autonomic nervous regulation. To further explain the parasympathetic and catecholamine effects, we hypothesized that endurance training could modify rat myocardial beta1, beta2, beta3 adrenoreceptors (AR) and M2 muscarinic cholinergic receptor (AchR) densities.
  
  
  METHODS
  Two groups of adults female Wistar rats were studied: controls (C) (N = 7) and trained (T) (N = 9). An 8-wk treadmill training protocol was performed, 5 d x wk and of 1 h x d. At the end of the training session, left ventricle and atria muscle were isolated and weighed. Then, quantification of beta1, beta2, beta3 AR and M2 AchR was performed using Western blot analysis.
  
  
  RESULTS
  M2 AchR densities were not modified in left ventricle or in atria by training (respectively, 100 +/- 22%, C vs 101 +/- 14%, T and 100 +/- 23%, C vs 119 +/- 30%, T). Concerning the left ventricle beta AR isoforms, beta1AR density was decreased in T (80 +/- 10% T vs 100 +/- 14% C, P = 0.01), beta2AR was unaltered (102 +/- 12%, T vs 100 +/- 17%, C), and beta3 AR density was increased in T (139 +/- 38% T vs 100 +/- 15% C; P < 0.05).
  
  
  CONCLUSIONS
  Our results show for the first time that in female rats an 8-wk treadmill training protocol alters specifically the left ventricle beta AR isoforms densities but not the M2 AchR one. These results could explain some of the beneficial cardiovascular adaptations of the physically trained heart.
authors.affiliation: Laboratory of Physiology and Biomechanics of Muscular Exercise. UFR-APS, University of Rennes 2, Rennes, France. Julie.barbier@uhb.fr
authors.forename: Julie
authors.initials: J
authors.lastname: Barbier
authors.forename: Françoise
authors.initials: F
authors.lastname: Rannou-Bekono
authors.forename: Jérome
authors.initials: J
authors.lastname: Marchais
authors.forename: Phanélie-Marie
authors.initials: PM
authors.lastname: Berthon
authors.forename: Paul
authors.initials: P
authors.lastname: Delamarche
authors.forename: François
authors.initials: F
authors.lastname: Carré
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005260:Female; D005602:France; D009206:Myocardium / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar; D043585:Receptor, Muscarinic M2 / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000145:classification / Q000378:metabolism*
chemical_list: D043585:Receptor, Muscarinic M2; D011943:Receptors, Adrenergic, beta