alpha1-adrenergic receptors activate AMP-activated protein kinase in rat hearts.
- Author:
Ming XU
1
;
Yan-Ting ZHAO
;
Yao SONG
;
Tian-Pao HAO
;
Zhi-Zhen LU
;
Qi-De HAN
;
Shi-Qiang WANG
;
You-Yi ZHANG
Author Information
1. Institute of Vascular Medicine, Peking University Third Hospital and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China.
- Publication Type:Journal Article
- MeSH:
AMP-Activated Protein Kinases;
metabolism;
Animals;
Cell Line;
Heart Ventricles;
Male;
Myocardium;
cytology;
metabolism;
Norepinephrine;
pharmacology;
Phenylephrine;
pharmacology;
Phosphorylation;
Rats;
Rats, Sprague-Dawley;
Receptors, Adrenergic, alpha;
physiology
- From:
Acta Physiologica Sinica
2007;59(2):175-182
- CountryChina
- Language:English
-
Abstract:
To test the hypothesis that AMP-activated protein kinase (AMPK) is possibly the downstream signaling molecule of certain subtypes of adrenergic receptor (AR) in the heart, we evaluated AMPK activation mediated by ARs in H9C2 cells, a rat cardiac source cell line, and rat hearts. The AMPK-alpha subunit and the phosphorylation level of Thr(172)-AMPK-alpha subunit were subjected to Western blot analysis. Osmotic minipumps filled with norepinephrine (NE), phenylephrine (PE) or vehicle [0.01% (W/V) vitamin C solution] were implanted into male Sprague-Dawley rats subcutaneously. The pumps delivered NE or PE continuously at the rate of 0.2 mg/kg per hour. After 7-day infusion, the activity of AMPK was examined following immunoprecipitation with anti-AMPK-alpha antibody. At the cellular level, we found that NE elevated AMPK phosphorylation level in a dose- and time-dependent manner, with the maximal effect at 10 micromol/L NE after 10-minute treatment. This effect was insensitive to propranolol, a specific beta-AR antagonist, but abolished by prazosin, an alpha(1)-AR antagonist, suggesting that alpha(1)-AR but not beta-AR mediated the phosphorylation of AMPK. Moreover, the results from rat models of 7-day-infusion of AR agonists demonstrated that the activity of AMPK was significantly higher in NE (7.4-fold) and PE (6.0-fold) infusion groups than that in the vehicle group (P<0.05, n=6). On the other hand, no obvious cardiac hypertrophy and tissue fibrosis changes were observed in PE-infused rats. Taken together, our results demonstrate that alpha(1)-AR stimulation enhances the activity of AMPK, indicating an important role of alpha(1)-AR stimulation in the regulation of AMPK in the heart. Understanding the activation of AMPK mediated by alpha(1)-AR might have clinical implications in the therapy of heart failure.
