beta(2)-Adrenergic stimulation attenuates left ventricular remodeling, decreases apoptosis, and improves calcium homeostasis in a rodent model of ischemic cardiomyopathy.
The benefit of the beta(2)-adrenergic agonist, clenbuterol, in left ventricular assist device patients with dilated cardiomyopathy has been reported, but its effect on ischemic heart failure (HF) is unknown. We investigated whether clenbuterol improves left ventricular remodeling, myocardial apoptosis and has synergy with a beta(1) antagonist, metoprolol, in a model of ischemic HF. Rats were randomized to: 1) HF only; 2) HF + clenbuterol; 3) HF + metoprolol; 4) HF + clenbuterol + metoprolol; and 5) rats with sham surgery. HF was induced by left anterior descending artery (LAD) artery ligation and confirmed by decreased left ventricular fractional shortening, decreased maximum left ventricular dP/dt (dP/dt(max)), and elevated left ventricular end-diastolic pressure (LVEDP) compared with sham rats (p < 0.01). After 9 weeks of oral therapy, echocardiographic, hemodynamic, and ex vivo end-diastolic pressure-volume relationship (EDPVR) measurements were obtained. Immunohistochemistry was performed for myocardial apoptosis and DNA damage markers. Levels of calcium-handling proteins were assessed by Western blot analysis. Clenbuterol-treated HF rats had increased weight gain and heart weights versus HF rats (p < 0.05). EDPVR curves revealed a leftward shift in clenbuterol rats versus metoprolol and HF rats (p < 0.05). The metoprolol-treated group had a lower LVEDP and higher dP/dt(max) versus the HF group (p < 0.05). Clenbuterol and metoprolol groups had decreased myocardial apoptosis and DNA damage markers and increased DNA repair markers versus HF rats (all p < 0.01). Protein levels of the ryanodine receptor and sarcoplasmic reticulum calcium-ATPase were improved in clenbuterol-, metoprolol-, and clenbuterol+metoprolol-treated groups versus HF rats. However, as a combination therapy, there were no synergistic effects of clenbuterol+metoprolol treatment. We conclude that clenbuterol ameliorates EDPVR, apoptosis, and calcium homeostasis but does not have synergy with metoprolol in our model of ischemic HF.
Xydas
Steve
S
Department of Surgery, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Kherani
Aftab R
AR
Chang
Jonathan S
JS
Klotz
Stefan
S
Hay
Ilan
I
Mutrie
Christopher J
CJ
Moss
Garrett W
GW
Gu
Anguo
A
Schulman
Allison R
AR
Gao
Daqing
D
Hu
Debora
D
Wu
Ed X
EX
Wei
Chiming
C
Oz
Mehmet C
MC
Wang
Jie
J
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004195:Disease Models, Animal; D004452:Echocardiography; D006439:Hemodynamics / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D017202:Myocardial Ischemia / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D020257:Ventricular Remodeling / Q000187:drug effects*
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D002118:Calcium