The hamster cheek pouch--an experimental model to study postischemic macromolecular permeability.

Area of Science:

• Physiology
• Microcirculation Research
• Vascular Biology

Background:

• Local ischemia can alter microvascular permeability.
• Understanding these changes is crucial for treating ischemic conditions.
• Intravital microscopy offers a direct method to study these effects.

Purpose of the Study:

• To establish and validate a hamster cheek pouch model for studying macromolecular permeability changes after local ischemia.
• To quantify the relationship between ischemic duration and the extent of vascular leakage.
• To assess the model's responsiveness to stimuli like histamine.

Main Methods:

• Eversion of the hamster cheek pouch for intravital microscopy.
• Induction of temporary local ischemia using a cuff for circulatory arrest.
• Quantification of macromolecular permeability via fluorescein-labeled dextran leakage (Mw 70,000).
• Testing vascular reactivity with locally applied histamine.

Main Results:

• Short ischemic periods (5 min) followed by reperfusion did not result in observable leaks.
• Ischemia prolonged to 30 min caused a temporary increase in postcapillary venular leaks.
• Repeated ischemic occlusions led to a diminished response.
• A 60-min occlusion period did not further increase macromolecular permeability.
• The cheek pouch model demonstrated reactivity to histamine.

Conclusions:

• The everted hamster cheek pouch model is suitable for studying increases in macromolecular permeability following local ischemia.
• The severity of permeability changes is dependent on the duration of ischemia.
• The model allows for the investigation of microvascular responses to ischemic events.