FIGURE 11.

Ca²⁺ dependence of the mPTP in rat adult cardiac myocytes. A: mPTP ROS threshold during a “clamp” of intracellular Ca²⁺ >500nM for >20 min (using 10-Hz electrical tetanization in 5 mM bathing Ca²⁺ in the presence of thapsigargin or cyclopiazonic acid to disable the sarcoplasmic reticulum) is identical to that in unstimulated cells (with a cytoplasmic Ca²⁺ of ∼100 nM). B: complete equimolar replacement of Ca²⁺ for Sr²⁺ (for 6 h) in intact cardiac myocytes resulted in the same mPTP ROS threshold as seen in cells with normal Ca²⁺. C: buffering intracellular Ca²⁺ (with BAPTA) or limiting Ca²⁺ influx (in nominally Ca²⁺-free buffer) does not limit cardiac myocyte death after hypoxia/reoxygenation. [From Juhaszova et al. (218). Republished with permission from the American Society for Clinical Investigation; permission conveyed through Copyright Clearance Center, Inc.]