Fig. 6. (A ) Ischemia causes a decrease in intracellular pH (pHⁱ) (open squares ) and APC limits the decrease of pHⁱ(closed squares ) during ischemia in young adult hearts (*P < 0.05). (B ) Ischemia causes a decrease in pHⁱ(open circles ) and APC limits the decrease of pHⁱ(closed circles ) during ischemia in middle-aged hearts (*P < 0.05). (C ) Ischemia causes a decrease in pHⁱ(open triangles ) and APC does not limit the decrease of pHⁱ(closed triangles ) during ischemia and reperfusion in aged hearts. n = 6/group. * APC versus  control.