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Microhemodynamics and leukocyte sequestration after pulmonary ischemia and reperfusion in rabbits
G E Kuhnle1, H Reichenspurner, T Lange
1Institute of Anesthesiology, University of Munich, Germany.
Objective:
Investigation of leukocyte sequestration in alveolar capillaries and of microhemodynamic changes after pulmonary ischemia/reperfusion injury.
Methods:
The kinetics of leukocyte passage and the hemodynamics in pulmonary microcirculation were investigated in 16 rabbits by intravital microscopy. Mean red blood cell velocity and the number of sticking leukocytes were measured in pulmonary arterioles, venules, and capillaries after 1 hour of tourniquet ischemia and 10 minutes and 1 hour after reperfusion.
Results:
The decrease of red blood cell velocity after reperfusion was associated with a largely increased heterogeneity of blood flow. Immediately after the onset of blood flow, sequestered leukocytes were found in all microvascular segments. An increased number of leukocytes was present in arterioles, venules, and alveolar capillaries 10 minutes and 1 hour after reperfusion. Concomitantly, width of alveolar septa was increased while arterial oxygen tension was reduced, indicating the development of interstitial pulmonary edema.
Conclusion:
Leukocytes are sequestered after pulmonary ischemia and reperfusion not only in alveolar capillaries but also in arterioles and venules, and they may contribute to the development of reperfusion edema.
Insights
Following pulmonary ischemia/reperfusion injury, leukocytes sequester in lung microvessels, contributing to reperfusion edema. This study investigated leukocyte sequestration and microhemodynamic changes in rabbits.
Area of Science:
- Pulmonary Medicine
- Cardiovascular Research
- Inflammation and Immunology
Background:
- Pulmonary ischemia/reperfusion (I/R) injury is a critical clinical issue.
- Leukocyte sequestration is implicated in I/R injury, but its precise location and role in the pulmonary microcirculation require further elucidation.
Purpose of the Study:
- To investigate leukocyte sequestration in pulmonary microcirculation after I/R injury.
- To examine microhemodynamic alterations, including red blood cell velocity and leukocyte behavior, in response to pulmonary I/R.
Main Methods:
- Intravital microscopy was employed in 16 rabbits to study pulmonary microcirculation.
- Leukocyte kinetics and red blood cell velocity were measured in arterioles, venules, and capillaries.
- Measurements were taken after 1 hour of ischemia and at 10 minutes and 1 hour post-reperfusion.
Main Results:
- Reperfusion led to decreased red blood cell velocity and increased blood flow heterogeneity.
- Leukocyte sequestration occurred across all microvascular segments (arterioles, venules, capillaries) post-reperfusion.
- Increased leukocyte counts correlated with widened alveolar septa and reduced arterial oxygen tension, indicating pulmonary edema.
Conclusions:
- Leukocyte sequestration extends beyond alveolar capillaries to pulmonary arterioles and venules following I/R injury.
- These sequestered leukocytes may play a significant role in the pathogenesis of reperfusion edema.
- Understanding these mechanisms is crucial for developing therapeutic strategies against pulmonary I/R injury.