Gender-Based Differences in Cardiac Repolarization in Mouse Ventricle

The mouse heart has become a widely used model for genetic studies of heart diseases. Thus, understanding gender differences in mouse cardiac repolarization is crucial to the interpretation of such studies. The objective of this study was to evaluate whether there are gender differences in cardiac repolarization in mouse ventricle and to gain insights into the ionic and molecular mechanisms underlying these differences. Action potential durations (APDs) and K currents in male and female ventricular myocytes were compared using a patch-clamp technique. APD20, APD50, and APD90 were found to be significantly longer in females than males. Examination of the different K currents revealed that a significantly lower current density exists in female ventricular myocytes compared with male myocytes for the ultrarapid delayed rectifier K current, IKur (at +30 mV, male, 33.2±2.9 pA/pF [n= 22]; female, 20.9±1.73 pA/pF [n= 19], P