Effect of β3-adrenergic receptor on atrial L-type Ca(2+) current in rats with chronic heart failure.
OBJECTIVE
To investigate the effect of selective β3-adrenoreceptor agonist BRL-37344 on L-type Ca(2+) current (Ica,L) and mRNA expression of L-type Ca(2+) channel α2δ-2 (Cacna2d2) in rats with chronic heart failure (CHF).


METHODS
Twenty-four male Wistar rats were divided into normal control (n=6) and CHF group (n=18), which were further divided into CHF control and BRL group (0.4nmol/kg, IV, twice weekly for four weeks). Echocardiography was performed to assess the structure and function of the left atrium (LA).


RESULTS
The LA in the BRL group (4.4 ± 0.2mm) was larger than in the normal control (3.5 ± 0.3mm, P<0.01) or CHF control (4.0 ± 0.2mm, P<0.05) group. The LA ejection fraction in the BRL group (36.2 ± 4.2%) was lower than in the normal control (58.0 ± 3.1%, P<0.01) or CHF control group (42.3 ± 4.8%, P<0.05). There was no difference in Ica,L density between the BRL group and CHF control group (8.3 ± 1.7 vs. 8.2 ± 2.6 pA/pF, P>0.05), which was higher than in the normal control group (6.0 ± 1.8 pA/pF, P<0.01). There was no difference in the mRNA expression of α2δ-2 (Cacna2d2) between the BRL group and CHF control group (0.264 ± 0.005 vs. 0.243 ± 0.017, P>0.05), which was also higher than in the normal control group (0.137 ± 0.013, P<0.01).


CONCLUSIONS
β3-Adrenoreceptor stimulation with BRL-37344 was associated with an increase in LA diameter and a decrease in LA function in chronic heart failure. These structural and function changes were not related to Ica,L or L-type Ca(2+) channel α2δ-2 (Cacna2d2) subunit in the LA myocytes.
Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.
Biao
B
Li
Department of Cardiology, The Red Cross Hospital of Guangzhou City, The Fourth Affiliated Hospital of Jinan University, Guangzhou 510220, PR China.
Qiang
Q
Zhao
School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
Le-Xin
LX
Wang
Guangdong Provincial Cardiovascular Institute, Guangdong Provincial People's Hospital Medical Research Center, Guangzhou 510080, PR China.
Chun-Yu
CY
Deng
Department of Cardiology, The Red Cross Hospital of Guangzhou City, The Fourth Affiliated Hospital of Jinan University, Guangzhou 510220, PR China.
Fang
F
Zeng
Department of Cardiology, The Red Cross Hospital of Guangzhou City, The Fourth Affiliated Hospital of Jinan University, Guangzhou 510220, PR China.
Tong-Guo
TG
Wu
Department of Cardiology, The Red Cross Hospital of Guangzhou City, The Fourth Affiliated Hospital of Jinan University, Guangzhou 510220, PR China.
Zuo-Feng
ZF
Jiang
Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China. Electronic address: lwang@csu.edu.au.
Ding-Li
DL
Xu
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002908:Chronic Disease; D004983:Ethanolamines / Q000494:pharmacology; D006325:Heart Atria / Q000378:metabolism / Q000503:physiopathology; D006333:Heart Failure / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D022702:Receptors, Adrenergic, beta-3 / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; C478374:Cacna2d2 protein, rat; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D004983:Ethanolamines; D022702:Receptors, Adrenergic, beta-3; C057368:BRL 37344; D002118:Calcium
Atrium; Heart failure; Rat; Ventricular function; β(3)-Adrenoreceptor