TY - JOUR
T1 - Possible involvement of stress-activated protein kinase signaling pathway and fas receptor expression in prevention of ischemia/reperfusion- induced cardiomyocyte apoptosis by carvedilol
AU - Yue, Tian Li
AU - Ma, Xin Liang
AU - Wang, Xinkang
AU - Romanic, Anne M.
AU - Liu, Gao Lin
AU - Louden, Calvert
AU - Gu, Juan Li
AU - Kumar, Sanjay
AU - Poste, George
AU - Ruffolo, Robert R.
AU - Feuerstein, Giora Z.
PY - 1998/2/9
Y1 - 1998/2/9
N2 - Carvedilol, a new vasodilating β-adrenoceptor antagonist and a potent antioxidant, produces a high degree of cardioprotection in a variety of experimental models of ischemic cardiac injury. Recent clinical studies in patients with heart failure have demonstrated that carvedilol reduces morbidity and mortality and inhibits cardiac remodeling. The present study was designed to explore whether the protective effects of carvedilol on the ischemic myocardium include inhibition of apoptosis of cardiomyocytes and, if so, to determine its mechanism of action. Anesthetized rabbits were subjected to 30 minutes of coronary artery occlusion followed by 4 hours of reperfusion. Detection of apoptosis of cardiomyocytes was based on the presence of nucleosomal DNA fragments on agarose gels (DNA ladder) and in situ nick end labeling. Carvedilol (1 mg/kg IV), administered 5 minutes before reperfusion, reduced the number of apoptotic myocytes in the ischemic area from 14.7±0.4% to 3.4±1.8% (77% reduction, P<.001). Propranolol, administered at equipotent β-blocking dosage, reduced the number of apoptotic myocytes to 8.94±2.1% (39% reduction, P<.05). DNA ladders were observed in the hearts of all six vehicle-treated rabbits but only one of six carvedilol-treated rabbits (P<.01). Immunocytochemical analysis of rabbit hearts demonstrated an upregulation of Fas protein in ischemic cardiomyocytes, and treatment with carvedilol reduced both the intensity of staining as well as the area stained. Myocardial ischemia/reperfusion led to a rapid activation of stress-activated protein kinase (SAPK) in the ischemic area but not in nonischemic regions. SAPK activity was increased from 2.1±0.3 mU/mg (basal) to 8.9±0.8 mU/mg after 30 minutes of ischemia followed by 20 minutes of reperfusion. Carvedilol inhibited the activation of SAPK by 53.4±6.5% (P<.05). Under the same conditions, propranolol (1 mg/kg) had no effect on SAPK activation. Taken together, these results suggest that carvedilol prevents myocardial ischemia/reperfusion-induced apoptosis in cardiomyocytes possibly by downregulation of the SAPK signaling pathway, by inhibition of Fas receptor expression, and by β-adrenergic blockade. The former two actions represent novel and important mechanisms that may contribute to the cardioprotective effects of carvedilol.
AB - Carvedilol, a new vasodilating β-adrenoceptor antagonist and a potent antioxidant, produces a high degree of cardioprotection in a variety of experimental models of ischemic cardiac injury. Recent clinical studies in patients with heart failure have demonstrated that carvedilol reduces morbidity and mortality and inhibits cardiac remodeling. The present study was designed to explore whether the protective effects of carvedilol on the ischemic myocardium include inhibition of apoptosis of cardiomyocytes and, if so, to determine its mechanism of action. Anesthetized rabbits were subjected to 30 minutes of coronary artery occlusion followed by 4 hours of reperfusion. Detection of apoptosis of cardiomyocytes was based on the presence of nucleosomal DNA fragments on agarose gels (DNA ladder) and in situ nick end labeling. Carvedilol (1 mg/kg IV), administered 5 minutes before reperfusion, reduced the number of apoptotic myocytes in the ischemic area from 14.7±0.4% to 3.4±1.8% (77% reduction, P<.001). Propranolol, administered at equipotent β-blocking dosage, reduced the number of apoptotic myocytes to 8.94±2.1% (39% reduction, P<.05). DNA ladders were observed in the hearts of all six vehicle-treated rabbits but only one of six carvedilol-treated rabbits (P<.01). Immunocytochemical analysis of rabbit hearts demonstrated an upregulation of Fas protein in ischemic cardiomyocytes, and treatment with carvedilol reduced both the intensity of staining as well as the area stained. Myocardial ischemia/reperfusion led to a rapid activation of stress-activated protein kinase (SAPK) in the ischemic area but not in nonischemic regions. SAPK activity was increased from 2.1±0.3 mU/mg (basal) to 8.9±0.8 mU/mg after 30 minutes of ischemia followed by 20 minutes of reperfusion. Carvedilol inhibited the activation of SAPK by 53.4±6.5% (P<.05). Under the same conditions, propranolol (1 mg/kg) had no effect on SAPK activation. Taken together, these results suggest that carvedilol prevents myocardial ischemia/reperfusion-induced apoptosis in cardiomyocytes possibly by downregulation of the SAPK signaling pathway, by inhibition of Fas receptor expression, and by β-adrenergic blockade. The former two actions represent novel and important mechanisms that may contribute to the cardioprotective effects of carvedilol.
KW - Apoptosis
KW - Cardiomyocyte
KW - Fas
KW - Ischemia
KW - Reperfusion
KW - Stress-activated protein kinase
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U2 - 10.1161/01.RES.82.2.166
DO - 10.1161/01.RES.82.2.166
M3 - Article
C2 - 9468187
AN - SCOPUS:0032498614
SN - 0009-7330
VL - 82
SP - 166
EP - 174
JO - Circulation Research
JF - Circulation Research
IS - 2
ER -