We examined if
sevoflurane given before cold ischemia of intact hearts (
anesthetic preconditioning, APC) affords additional protection by further improving mitochondrial energy balance and if this is abolished by a mitochondrial KATP blocker.
NADH and
FAD fluorescence was measured within the left ventricular wall of 5 groups of isolated guinea pig hearts: (1)
hypothermia alone; (2) hypothermia+ischemia; (3) APC (4.1%
sevoflurane)+cold ischemia; (4) 5-HD+cold
ischemia, and (5) APC+5-HD+cold
ischemia. Hearts were exposed to
sevoflurane for 15 minutes followed by 15 minutes of washout at 37 degrees C before cooling, 2 hours of 27 degrees C
ischemia, and 2 hours of 37 degrees C reperfusion. The
KATP channel inhibitor 5-HD was perfused before and after
sevoflurane.
Ischemia caused a rapid increase in
NADH and a decrease in
FAD that waned over 2 hours. Warm reperfusion led to a decrease in
NADH and an increase in
FAD. APC attenuated the changes in
NADH and
FAD and further improved postischemic function and reduced
infarct size. 5-HD blocked the cardioprotective effects of APC but not APC-induced alterations of
NADH and
FAD. Thus, APC improves redox balance and has additive cardioprotective effects with mild hypothermic
ischemia. 5-HD blocks APC-induced cardioprotective effects but not improvements in mitochondrial bioenergetics. This suggests that mediation of protection by
KATP channel opening during cold ischemia and reperfusion is downstream from the APC-induced improvement in redox state or that these changes in redox state are not attenuated by
KATP channel antagonism.