Figure 4.

Response to step decreases in extracellular PO₂ from 40 to 1 mmHg. (A–D) In the upper panels, core IFM and SSM responses are shown in black and red, respectively: (A) local PO₂, (B) proton pump activity, (C) mitochondrial inner membrane potential, and (D) mitochondrial ATPase activity. (E–H) Lower panels show the response averaged over the entire cell: (E) CrP concentration (black), ATP concentration (red), and ATP concentration in submembrane space (blue); (F) Ca²⁺ transient (inset, single transient at 0 (blue) and 120 s (red) after ischemia onset); (G) activity of sarcolemmal ATPase (black) and SERCA (red); and (H) developed force. To see this figure in color, go online.