Figure 3.

Ca²⁺, ROS and CypD are involved in tPTP opening. (A) Frequency of tPTP openings (using TMRM to assess ΔΨ_m) in wild-type (WT) mice in the presence and absence of Ru360 or CsA, and in MCU- and CypD-knockout (KO) mice (**P<0.01, vs CTL, n=6-9). Data were acquired from both permeabilized (with the SR Ca²⁺ release protocol, as in Fig 1. Influence of 1 μmol/L H₂O₂ on tPTP frequency) and intact cells (at 1Hz pacing frequency in the absent and the present of ISO) (B), and the time point at which tPTP opening occurred and its duration of opening (C; n= 6-7). (D) Frequency of tPTP openings as a function of [Ca²⁺]_i with and without 1 μmol/L H₂O₂ (± CsA; n=5-8 for each [Ca²⁺]_i and Ca²⁺clamp treatment). (E) Transient ΔΨ_m depolarization in individual mitochondria, during 1Hz pacing in intact myocytes. Images are taken from times marked by * during time course at right. Arrows mark mitochondrion (or pair) that displayed transient ΔΨ_m changes (Scale bar =4 μm). (F) Frequency of intact myocyte tPTP events and percentage of mitochondria in tPTP openings at any time (±CsA).