The purpose of the present study was to determine if repetitive
myocardial ischemia would result in the cumulative loss of mitochondrial
adenine nucleotides. Isolated perfused rat hearts were subjected to continuous or intermittent
ischemia. A single 5-minute period of continuous
ischemia did not result in a significant decrease in the mitochondrial
adenine nucleotide pool; a single 10-minute period of
ischemia resulted in a decrease of approximately 17%. Next, the
adenine nucleotide content of mitochondria from preischemic and 30-minute continuous ischemic hearts was compared with two groups of hearts undergoing intermittent
ischemia (both groups receiving a total of 30 minutes of
ischemia). One group received three 10-minute episodes of
ischemia interrupted by 5-minute periods of reperfusion (3 x 10-minute intermittent
ischemia); the other intermittent ischemic group received six 5-minute episodes of
ischemia interrupted by 5-minute periods of perfusion (6 x 5-minute intermittent
ischemia). The mitochondrial
adenine nucleotide content (expressed as nanomoles per nanomole
cytochrome a) for the preischemic and 30-minute continuous ischemic hearts was 14.7 +/- 0.6 and 8.0 +/- 0.4, respectively. The mitochondrial
adenine nucleotide content of the 3 x 10-minute intermittent
ischemia group (8.5 +/- 0.5) was not significantly different from the 30-minute continuous ischemic group. The mitochondrial
adenine nucleotide content of the 6 x 5-minute intermittent
ischemia group (11.0 +/- 0.6) was significantly larger than that of the 30-minute continuous and the 3 x 10-minute intermittent
ischemia groups (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)