Sex Hormones Prolong the QT Interval and Downregulate Potassium Channel Expression in the Rabbit Heart

Abstract

The association between hormone-induced changes in baseline QT interval and the mRNA level for these channels suggests that sex hormones may play a critical role in regulating cardiac repolarization. However, the changes in baseline QT and potassium channel mRNA after hormone treatment were not concordant with the changes in QT interval after the infusion of quinidine, after which E2-treated animals responded similarly to controls (18.4 +/- 4.6% and 19.3 +/- 4.6% increase in QT interval, respectively) and DHT-treated animals exhibited less QT prolongation (11.4 +/- 3.8% increase; P < .03).