Upregulation of β3-adrenergic receptor expression in the atrium of rats with chronic heart failure.

Objectives: To investigate the expression of beta(3)-adrenergic receptor (beta(3)-AR) in the atrium of rats with chronic heart failure (CHF). Methods: The heart failure rat model was established by aortic constriction. Thirty-six male Wistar rats were divided into Sham group (n = 10) and heart failure model group (n 26), which were further divided into CHF control (CHF group) and BRL group. The rats in the BRL group were treated with a selective beta(3)-AR agonist, BRL-37344 (4.0 nmol/kg, twice weekly) for 4 weeks. Results: In the BRL group, the left ventricular end-systolic pressure (83.21 +/- 13.0 vs 101.50 +/- 12.12 mm Hg) and the absolute values of the maximal rate of rise and fall of left ventricular pressure ([+/- dP/dtmax] 2.81 +/- 0.04 vs 0.35 +/- 0.04 and - 2.72 +/- 0.06 vs - 3.33 +/- 0.06) were lower than in the CHF group (P <.01). The left atrial mass index (LAMI) in the BRL group (0.4132 +/- 0.0306) was higher than that in the CHF (0.3212 +/- 0.0136) or Sham group (0.2683 +/- 0.0145; P <.01). The levels of the left atrial beta(3)-AR messenger RNA (mRNA) expression in the BRL group (0.932 +/- 0.055) was higher than that in the CHF (0.706 +/- 0.043) or Sham group (0.310 +/- 0.020; P <.01). In all animals, there was a positive correlation between the level of beta(3)-AR mRNA expression and the left or right atrial mass index (correlation coefficient ranged from 0.744 to 0.937). Conclusion: There is a significant increase in the beta(3)-AR mRNA expression in the atrium of rats with heart failure. The level of beta(3)-AR mRNA expression was associated with the AMI and was enhanced by a selective beta(3)-AR agonist, BRL-37344.