Cardiotrophin-1 （CT-1） activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expres- sion pattern of sarcomeric...Cardiotrophin-1 （CT-1） activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expres- sion pattern of sarcomeric contractile protein α-actin, specialized eytoskeletal protein α-actinin and mitochondrial uncoupling protein-2 （UCP2） in myocardial remodeling induced by chronic exposure to CT-1. Kunming mice were intraperitoneally injected with carboxy-terminal polypeptide （CP） of CT-1 （CT-1-CP, 500 μg·kg-1·day^-1） for 1, 2, 3 and 4 week （s）, respectively （4 groups obtained according to the injection time, n=10 each, with 5 males and 5 females in each group）, Those injected with physiological saline for 4 weeks served as controls （n=10, with 5 males and 5 females）. The heart tissues of mice were harvested at 1, 2, 3 or 4 week （s）. Immunohistochemistry （IHC） and Western blotting （WB） were used to detect the distribution and expression of sarcomeric α-actin, α-aetinin and mitoehondrial UCP2 in myocardial tissues. IHC showed that α-actin was mainly distributed around the nuclei of cardiomyo- cytes, α-actinin concentrated around the striae and UCP2 scattered rather evenly in the plasma. The ex- pression of α-actin was slightly greater than that of α-actinin and UCP2 in the control group （IHC： χ^2=6.125; WB： F=0.249, P〉0.05） and it gradually decreased after exposure to CT-1-CP. There was no significant difference in the expression of α-actin between the control group and the CT-1-CP-treated groups （χ^2=7.386, P〉0.05）. But Western blotting revealed significant difference in the expression of α-actin between the control group and the 4-week CT-1-CP-treated group （F=2.912; q=4.203, P〈0.05）. Moreover, it was found that the expression of α-actinin increased stepwise with the exposure time in CT-1-CP-treated groups and differed significantly between CT-1-CP-treated groups and the control group （ICH： χ^2=21.977; WB： F=50.388; P〈0.01）. The expression of UCP2 was initially increased （WB： control group vs. 1- or 2-week group, q values： 5.603 and 9.995, respectively, P〈0.01） and then de- creased （WB： control group vs. 3-week group, q=4.742, P〈0.01; control group vs. 4-week group, q=0.558, P〉0.05）. It was suggested that long-term exposure to CT-1-CP could lead to the alteration in the expression of sarcomeric α-actin, α-actinin and mitochonclrial UCP2. The different expressions of sarcomeric structure proteins and mitochondrial UCP2 may be involved in myocardial remodeling.展开更多
The chronic effects of carboxyl-terminal polypeptide of Cardiotrophin-1（CT-1-CP） on ventricular electrical remodeling were investigated. CT-1-CP, which contains 16 amino acids in sequence of the C-terminal of Cardio...The chronic effects of carboxyl-terminal polypeptide of Cardiotrophin-1（CT-1-CP） on ventricular electrical remodeling were investigated. CT-1-CP, which contains 16 amino acids in sequence of the C-terminal of Cardiotrophin-1, was selected and synthesized, and then administered to Kunming mice（aged 5 weeks） by intraperitoneal injection（500 ng·g^-1·day^-1）（4 groups, n=10 and female： male=1：1 in each group） for 1, 2, 3 and 4 weeks, respectively. The control group（n=10, female：male=1：1） was injected by physiological saline for 4 weeks. The epicardial monophasic action potential（MAP） was recorded by using a contact-type MAP electrode placed vertically on the left ventricular（LV） epicardium surface, and the electrocardiogram（ECG） signal in lead Ⅱ was monitored synchronously. ECG intervals（RR, PR, QRS and QT） and the amplitude of MAP（Am）, the maximum upstroke velocity（Vmax）, as well as action potential durations（APDs） at different repolarization levels（APD30, APD50, APD70, and APD90） of MAP were determined and analyzed in detail. There were no significant differences in RR and P intervals between CT-1-CP-treated groups and control group, but the PR segment and the QRS complex were greater in the former than in the latter（F=2.681 and 5.462 respectively, P〈0.05）. Though QT interval and the corrected QT interval（QTc） were shorter in CT-1-CP-treated groups than in control group, the QT dispersion（QTd） of them was greater in the latter than in the former（F=3.090, P〈0.05） and increased with the time. The ECG monitoring synchronously with the MAP showed that the compression of MAP electrode on the left ventricular epicardium induced performance similar to myocardium ischemia. As compared with those before chest-opening, the PR segment and QT intervals remained basically unchanged in control group, but prolonged significantly in all CT-1-CP-treated groups and the prolongation of QT intervals increased gradually along with the time of exposure to CT-1-CP. The QRS complex had no significant change in control group, one-week and three-week CT-1-CP-treated groups, but prolonged significantly in two-week and four-week CT-1-CP-treated groups. Interestingly, the QTd after chest-opening was significantly greater than that before chest-opening in control group（t=5.242, P〈0.01）, but decreased along with the time in CT-1-CP-treated groups. The mean MAP amplitude, Vmax and APD were greater in CT-1-CP-treated groups than those in control group, and became more obvious along with the time. The APD in four CT-1-CP-treat groups was prolonged mainly in middle to final repolarization phase. The difference among these groups became significant in middle phase（APD50）（F=6.076, P〈0.01） and increased furthermore in late and final phases（APD70： F=10.054; APD90： F=18.691, P〈0.01） along with the time of injection of CT-1-CP. The chronic action of CT-1-CP might induce the adapting alteration in cardiac conductivity and ventricular repolarization. The amplitude and the Vmax of the anterior LV epicardial MAP increased obviously, and the APD prolonged mainly in late and final phase of repolarization.展开更多
文摘Cardiotrophin-1 （CT-1） activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expres- sion pattern of sarcomeric contractile protein α-actin, specialized eytoskeletal protein α-actinin and mitochondrial uncoupling protein-2 （UCP2） in myocardial remodeling induced by chronic exposure to CT-1. Kunming mice were intraperitoneally injected with carboxy-terminal polypeptide （CP） of CT-1 （CT-1-CP, 500 μg·kg-1·day^-1） for 1, 2, 3 and 4 week （s）, respectively （4 groups obtained according to the injection time, n=10 each, with 5 males and 5 females in each group）, Those injected with physiological saline for 4 weeks served as controls （n=10, with 5 males and 5 females）. The heart tissues of mice were harvested at 1, 2, 3 or 4 week （s）. Immunohistochemistry （IHC） and Western blotting （WB） were used to detect the distribution and expression of sarcomeric α-actin, α-aetinin and mitoehondrial UCP2 in myocardial tissues. IHC showed that α-actin was mainly distributed around the nuclei of cardiomyo- cytes, α-actinin concentrated around the striae and UCP2 scattered rather evenly in the plasma. The ex- pression of α-actin was slightly greater than that of α-actinin and UCP2 in the control group （IHC： χ^2=6.125; WB： F=0.249, P〉0.05） and it gradually decreased after exposure to CT-1-CP. There was no significant difference in the expression of α-actin between the control group and the CT-1-CP-treated groups （χ^2=7.386, P〉0.05）. But Western blotting revealed significant difference in the expression of α-actin between the control group and the 4-week CT-1-CP-treated group （F=2.912; q=4.203, P〈0.05）. Moreover, it was found that the expression of α-actinin increased stepwise with the exposure time in CT-1-CP-treated groups and differed significantly between CT-1-CP-treated groups and the control group （ICH： χ^2=21.977; WB： F=50.388; P〈0.01）. The expression of UCP2 was initially increased （WB： control group vs. 1- or 2-week group, q values： 5.603 and 9.995, respectively, P〈0.01） and then de- creased （WB： control group vs. 3-week group, q=4.742, P〈0.01; control group vs. 4-week group, q=0.558, P〉0.05）. It was suggested that long-term exposure to CT-1-CP could lead to the alteration in the expression of sarcomeric α-actin, α-actinin and mitochonclrial UCP2. The different expressions of sarcomeric structure proteins and mitochondrial UCP2 may be involved in myocardial remodeling.
文摘The chronic effects of carboxyl-terminal polypeptide of Cardiotrophin-1（CT-1-CP） on ventricular electrical remodeling were investigated. CT-1-CP, which contains 16 amino acids in sequence of the C-terminal of Cardiotrophin-1, was selected and synthesized, and then administered to Kunming mice（aged 5 weeks） by intraperitoneal injection（500 ng·g^-1·day^-1）（4 groups, n=10 and female： male=1：1 in each group） for 1, 2, 3 and 4 weeks, respectively. The control group（n=10, female：male=1：1） was injected by physiological saline for 4 weeks. The epicardial monophasic action potential（MAP） was recorded by using a contact-type MAP electrode placed vertically on the left ventricular（LV） epicardium surface, and the electrocardiogram（ECG） signal in lead Ⅱ was monitored synchronously. ECG intervals（RR, PR, QRS and QT） and the amplitude of MAP（Am）, the maximum upstroke velocity（Vmax）, as well as action potential durations（APDs） at different repolarization levels（APD30, APD50, APD70, and APD90） of MAP were determined and analyzed in detail. There were no significant differences in RR and P intervals between CT-1-CP-treated groups and control group, but the PR segment and the QRS complex were greater in the former than in the latter（F=2.681 and 5.462 respectively, P〈0.05）. Though QT interval and the corrected QT interval（QTc） were shorter in CT-1-CP-treated groups than in control group, the QT dispersion（QTd） of them was greater in the latter than in the former（F=3.090, P〈0.05） and increased with the time. The ECG monitoring synchronously with the MAP showed that the compression of MAP electrode on the left ventricular epicardium induced performance similar to myocardium ischemia. As compared with those before chest-opening, the PR segment and QT intervals remained basically unchanged in control group, but prolonged significantly in all CT-1-CP-treated groups and the prolongation of QT intervals increased gradually along with the time of exposure to CT-1-CP. The QRS complex had no significant change in control group, one-week and three-week CT-1-CP-treated groups, but prolonged significantly in two-week and four-week CT-1-CP-treated groups. Interestingly, the QTd after chest-opening was significantly greater than that before chest-opening in control group（t=5.242, P〈0.01）, but decreased along with the time in CT-1-CP-treated groups. The mean MAP amplitude, Vmax and APD were greater in CT-1-CP-treated groups than those in control group, and became more obvious along with the time. The APD in four CT-1-CP-treat groups was prolonged mainly in middle to final repolarization phase. The difference among these groups became significant in middle phase（APD50）（F=6.076, P〈0.01） and increased furthermore in late and final phases（APD70： F=10.054; APD90： F=18.691, P〈0.01） along with the time of injection of CT-1-CP. The chronic action of CT-1-CP might induce the adapting alteration in cardiac conductivity and ventricular repolarization. The amplitude and the Vmax of the anterior LV epicardial MAP increased obviously, and the APD prolonged mainly in late and final phase of repolarization.
