Incidence of Cai2+ and APD alternans with pinacidil (Pin) treatment of monolayers at room temperature. A: incidence of Cai2+ alternans in control (Con) and after 15-min washin of 50 μM Pin. B: incidence of APD alternans for similar Pin treatment. Left, arrows and numbers show the fate of NA, AC, and AD monolayers with Pin exposure. Right, windows of 1:1 capture, AVW, and AVWD for NA, AC, and AD monolayers before (Con) and after the addition of Pin. In the Con columns, PCLC, PCLD, and MCL and windows of 1:1 capture, AVW, and AVWD are defined as in Fig. 3. In the Pin columns, MCL is averaged from all monolayers in the group, AVW from all A monolayers in the group, and AVWD from all AD monolayers in the group. See the Supplemental Material for further explanation. Error bars are not shown but are given in Supplemental Table S4.