Recurrent ischemia in the canine heart causes recurrent bursts of free radical production that have a cumulative effect on contractile function. A pathophysiological basis for chronic myocardial "stunning".
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Implication
Randomized trial shows recurrent ischemia reduces heart function in dogs, indicating cumulative oxidative damage.
Key Points
- This study aims to investigate how recurrent ischemic episodes affect heart function and oxidative stress in dogs.
- 117 open-chest dogs were subjected to 10 cycles of 5-min coronary occlusions and 10-min reperfusions.
- Systolic thickening fraction was measured 9 min after each reperfusion (R) to assess cardiac function after ischemia.
- Free radical production was measured using alpha-phenyl N-tert-butyl nitrone (PBN) following the ischemic episodes.
- Initial ischemic episodes caused significant decreases in contractility, while cumulative effects were evident after 10 cycles.
- Free radical bursts were observed after the 1st, 5th, and 10th reperfusions, with a 58% reduction in adducts after the 5th reperfusion (P < 0.05).
- Administration of mercaptopropionyl glycine improved functional recovery and reduced oxidative stress; effects diminished when treatment was halted early.
Cite This Study
Bolli et al. (1995) studied this question.