Effects Of Atorvastatin On Ⅰ_to Of The Simulated Ischemia Myocytes In Rat Left Ventricle

Objective:1. To observe the effects of atorvastatin on transient outward potassium (Ito) of the normal myocytes in rat left ventricle.2. To observe the effects of simulated ischemia on Ito of the myocytes in rat left ventricle.3. To observe the effects of atorvastatin on Ito of the simulated ischemia myocytes in rat left ventricle.Methods:Thirty-two Wistar rats were used for isolating left ventricular myocytes, which were randomly divided into four groups:Control group (normal solution), Atorvastatin group (normal with 5μmol/L atorvastatin), Ischemia group (simulated ischemia solution) and Ischemia-atorvastatin group (simulated ischemia with 5μmol/L atorvastatin). Ito were recorded in normal condition (basic state) by whole-cell patchclamp, and were recorded at 5,10,15 and 20 min after perfusion. The results were expressed by mean±SD. Continuous variables were compared by ANOVA of repeated measurement data, and p values< 0.05 were considered significant.Results:1. Normalized currents (at 50 mV), compared with basic state, there were no significant differences in control group after perfusion, while in atorvastatin group, ischemia group and ischemia-atorvastatin group, when perfused 5 min, the currents were decreased by 13.60%±5.74%,17.94%±3.18% and 21.87%±4.36%(P= 0.001, P= 0.000 and P= 0.000, respectively), and there were no differences among the three groups, and Ito was continuously decreased in atorvastatin group and ischemia group.2. Gate parameters, compared with basic state, when perfused 5 min, in atorvastatin group, the membrane potential at 50% maximal activation (V1/2,a) increased by 5.70%±2.43% (P= 0.001), and the membrane potential at 50% maximal inactivation (V1/2,i) increased by 16.32%±13.41% (P= 0.001), while in ischemia group and ischemia-atorvastatin group, V1/2,a decreased by 6.95%±3.13% and 12.56%±5.75% (P= 0.002 and P= 0.005, respectively), and V1/2,i decreased by 31.80%±14.06% and 36.66%±15.52% (P= 0.000 and P= 0.000, respectively); for V]/2,a and V1/2,i, there were no differences between Ischemia group and Ischemia-atorvastatin group, but both were significant differences when compared with atorvastatin group respectively.Conclusions:1. Atorvastatin plays a time dependent role like potassium channel block in rat left ventricular myocytes.2. During twenty minutes of simulated ischemia, Ito are continuously decreased.3. There is no effects of 5μmol/L atorvastatin on Ito in the state of simulated ischemia within twenty minutes.4. The effects of atorvastatin and simulated ischemia on V1/2,a and V1/2,i of Ito are different. V1/2,a and V1/2,i are increased after the perfusion of 5μmol/L atorvastatin, V1/2,a and V1/2,i are decreased after the perfusion of simulated ischemia solution.