Figure 2.

Simulated action potentials duration (APD) and APD alternans. (A) APD for the 1000th paced beat at a cycle length of 1000 ms in single endocardial cells. APDs with no hormone (NH; Table S1 the Methods in Supplementary Material) and two physiological concentrations of DHT (10 and 35 nM) in male cells are shown in left. Estradiol and progesterone at different physiological concentrations corresponding to three stages of the menstrual cycle were added in female cells (right). (B) Male epicardial cells with DHT treatment developed alternans at fast pacing rates, between cycle lengths 180 and 210 ms. (C) In female epicardial cells alternans developed at a much slower basic cycle length during the late follicular phase (pink) compared to luteal (green) and early follicular (red). I_Kr block increased susceptibility to alternans development in male (black in B) and dramatically in female models (black in C).