Susceptibility to ischemia-induced ventricular fibrillation in isolated female rat hearts varies moderately with estrous cycle stage

In conclusion, the susceptibility of isolated female rat hearts to ischemic VF is comparable to that of male rat hearts, meaning that isolated female rat hearts can be used as controls in studies to assess antiarrhythmic drug efficacy. Since female rats can be used for isolated heart studies of ischemic VF, the need to cull female rats is reduced. However, the variation in VF susceptibility in female rat hearts that is associated with the different stages of the estrous cycle may affect statistical power that could potentially lead to Type II statistical errors. This problem can be prevented with careful randomization.