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 center dot g(-1)center dot 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 (APD(30), APD(50), APD(70), and APD(90)) of MAP were determined C59 ic50 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 smaller than 0.05). Though QT interval ZD1839 research buy and the corrected

QT interval (QTc) were shorter in CT-1-CP-treated groups than in control group, the QT dispersion (QT(d)) of them was greater in the latter than in the former (F=3.090, P smaller than 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 check details CT-1-CP-treated groups. Interestingly, the QT(d) after chest-opening was significantly greater than that before chest-opening in control group (t=5.242, P smaller than 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 (APD(50)) (F=6.076, P smaller than 0.01) and increased furthermore in late and final phases (APD(70): F=10.054; APD(90): F=18.691, P smaller than 0.01) along with the time of injection of CT-1-CP.