Effect of training on beta1 beta2 beta3 adrenergic and M2 muscarinic receptors in rat heart.
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.
Barbier
Julie
J
Laboratory of Physiology and Biomechanics of Muscular Exercise. UFR-APS, University of Rennes 2, Rennes, France. Julie.barbier@uhb.fr
Rannou-Bekono
Françoise
F
Marchais
Jérome
J
Berthon
Phanélie-Marie
PM
Delamarche
Paul
P
Carré
François
F
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*
D043585:Receptor, Muscarinic M2; D011943:Receptors, Adrenergic, beta