Effect of ranolazine on the fast sodium channel current in rabbit atrial myocytes and use-dependent blockade / 西安交通大学学报(医学版)

Objective To explore the effect of ranolazine on the fast sodium channel current (INa) in rabbit atrial myocytes and the existence of use-dependent blockade. Methods Standard whole cell patch clamp technique was used to study the effect of ranolazine on the fast sodium channel current and the use-dependent blockade caused with different frequencies (1Hz, 3.3Hz and 5Hz) to stimulate the cells. Results The 30μmol/L ranolazine significantly reduced INa with an IC_(50) value of (25.6±1.8)μmmol/L and produced a frequency-dependent inhibitory effect on INa with obvious use-dependence. Conclusion Ranolazine can inhibit the fast sodium channel current in rabbit atrial myocytes and indeed has a use-dependent effect.

Tp-e/QT ratio as a predictive index of sudden cardiac death in patients with ST-segment elevation myocardial infarction / 西安交通大学学报(医学版)

Objective To detect Tp-e/QT ratio in patients with acute ST-segment elevation myocardial infarction (STEMI) and explore its clinical significance. Methods Healthy individuals and patients with acute STEMI were recruited in this study. Their first QTc,QTd and Tp-e were measured within 24 h after admission to hospital,and Tp-e/QT ratio was calculated so as to analyze the relation between Tp-Te/QT ratio and malignant ventricular arrhythmia. Results Compared with those of the healthy individuals,the intervals of QTd,Tp-e and QTc were significantly lengthened \[(33.66?16.76)ms vs. (55.29?31.12)ms,(89.55?12.61)ms vs. (142.65?39.33)ms,and (426.57?65.03)ms vs. (482.26?48.03)ms,P