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Updated: Mar 18, 2026
Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Dissecting the Effects of Ischemia and Reperfusion on the Coronary Microcirculation in a Rat Model of Acute
Maurits R Hollander1,2, Guus A de Waard1,2, Lara S F Konijnenberg1,2
1Department of Cardiology, VU Medical Center, Amsterdam, The Netherlands.
Background:
Microvascular injury (MVI) after coronary ischemia-reperfusion is associated with high morbidity and mortality. Both ischemia and reperfusion are involved in MVI, but to what degree these phases contribute is unknown. Understanding the etiology is essential for the development of new potential therapies.
Methods And Findings:
Rats were divided into 3 groups receiving either 30 minutes ischemia, 90 minutes ischemia or 30 minutes ischemia followed by 60 minutes reperfusion. Subsequently hearts were ex-vivo perfused in a Langendorff-model. Fluorescence and electron microscopy was used for analysis of capillary density, vascular permeability and ultrastructure. Most MVI was observed after 30 minutes ischemia followed by 60 minutes reperfusion. In comparison to the 30' and 90' ischemia group, wall thickness decreased (207.0±74 vs 407.8±75 and 407.5±71, p = 0.02). Endothelial nuclei in the 30'-60' group showed irreversible damage and decreased chromatin density variation (50.5±9.4, 35.4±7.1 and 23.7±3.8, p = 0.03). Cell junction density was lowest in the 30'-60' group (0.15±0.02 vs 2.5±0.6 and 1.8±0.7, p<0.01). Microsphere extravasation was increased in both the 90' ischemia and 30'-60' group.
Conclusions:
Ischemia alone for 90 minutes induces mild morphological changes to the coronary microcirculation, with increased vascular permeability. Ischemia for 30 minutes, followed by 60 minutes of reperfusion, induces massive MVI. This shows the direct consequences of reperfusion on the coronary microcirculation. These data imply that a therapeutic window exists to protect the microcirculation directly upon coronary revascularization.
Insights
Reperfusion significantly contributes to microvascular injury (MVI) after heart attacks. Short ischemia followed by reperfusion causes more damage than prolonged ischemia alone, suggesting a therapeutic window for protection.
Area of Science:
- Cardiovascular Science
- Microcirculation Research
- Ischemia-Reperfusion Injury
Background:
- Microvascular injury (MVI) following coronary ischemia-reperfusion is a major cause of morbidity and mortality.
- The relative contributions of ischemia and reperfusion to MVI are not well understood.
- Identifying the primary drivers of MVI is crucial for developing effective therapeutic strategies.
Purpose of the Study:
- To investigate the distinct roles of ischemia duration and subsequent reperfusion in causing coronary microvascular injury.
- To quantify the morphological and functional changes in the coronary microcirculation under different ischemia-reperfusion scenarios.
- To determine if a therapeutic window exists to mitigate MVI during revascularization.
Main Methods:
- Animal model: Rats subjected to 30 minutes ischemia, 90 minutes ischemia, or 30 minutes ischemia followed by 60 minutes reperfusion.
- Ex vivo perfusion: Hearts were analyzed using a Langendorff model.
- Microscopy: Fluorescence and electron microscopy were employed to assess capillary density, vascular permeability, and ultrastructure.
Main Results:
- Massive MVI was observed after 30 minutes ischemia followed by 60 minutes reperfusion, significantly more than ischemia alone.
- The 30-minute ischemia/60-minute reperfusion group showed decreased capillary wall thickness and significantly lower cell junction density.
- Endothelial cells in the 30'-60' group exhibited irreversible damage, and microsphere extravasation was increased in both 90' ischemia and 30'-60' groups.
Conclusions:
- Ischemia alone, even for 90 minutes, causes mild microcirculatory changes and increased permeability.
- Reperfusion following a shorter ischemic period (30 minutes) induces substantial microvascular injury.
- These findings highlight the critical role of reperfusion in MVI and suggest a potential therapeutic window for microcirculatory protection during revascularization.
