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Regional cerebral blood flow measurement in rats with radioactive microspheres
Insights
The method of heart catheterization impacts cerebral blood flow (CBF) measurements in rats. Atrial catheterization is preferred for accurate, symmetrical CBF assessment during experimental conditions.
Area of Science:
- Physiology
- Neurology
- Cardiovascular Research
Background:
- Accurate measurement of cerebral blood flow (CBF) is crucial for understanding brain function and disease.
- Radioactive microsphere techniques are commonly used to quantify regional CBF.
- The influence of catheterization methods on CBF measurements requires careful consideration.
Purpose of the Study:
- To evaluate the effect of different heart catheterization techniques on the measurement of cerebral blood flow (CBF) using radioactive microspheres in rats.
- To compare CBF measurements in cerebral hemispheres under various physiological conditions (anesthesia, hypoxia, hypercapnia) based on catheter insertion site.
Main Methods:
- Male Sprague-Dawley rats underwent catheterization via the right carotid artery, right subclavian artery, or directly into the left atrium for microsphere injection.
- Cerebral blood flow was measured in cortical and subcortical tissues under control, hypoxic, and hypercapnic conditions.
- Comparison of CBF between cerebral hemispheres based on catheterization method and experimental condition.
Main Results:
- Under control conditions, CBF was symmetrical between hemispheres in subclavian artery and atrial catheterized rats, but higher in the left cortex of carotid catheterized rats.
- During hypoxia and hypercapnia, atrial catheterization resulted in equal CBF increases in both hemispheres.
- Carotid catheterization led to attenuated CBF increases in the ipsilateral hemisphere during hypoxia and hypercapnia, despite similar percentage increases.
Conclusions:
- Carotid artery catheterization with ligation can limit the accurate assessment of regional cerebral blood flow changes, particularly under experimental conditions.
- Atrial catheterization is the recommended method for studies requiring comparable measurements of cerebral blood flow changes in both cerebral hemispheres.
Abstract:
The effect of the method of heart catheterization on the measurement of cerebral blood flow (CBF) with radioactive microspheres was evaluated during various experimental procedures in male Sprague-Dawley rats. Catheters were inserted into the left ventricle via the right carotid or right subclavian artery or directly into the left atrium for microsphere injections. CBF was measured in cerebral cortical and subcortical tissues under control anesthetized (70% N2O, 30% O2), hypoxic or hypercapnic test conditions. Under control conditions, CBF was similar in the right vs the left cerebral hemisphere in subclavian artery and atrial catheterized rats but was greater in the left vs the right cortex in carotid catheterized animals (p less than .05). During hypoxia and hypercapnia CBF increased equally in both cerebral hemispheres in atrial catheterized rats. The increase in CBF was significantly attenuated in the cerebral hemisphere ipsilateral to carotid catheterization during hypoxia and hypercapnia, although the percentage increase in flow was similar in both hemispheres. The results indicate the limitations of measuring regional CBF changes under experimental test conditions in rats with a ligated carotid artery and suggest that atrial catheterization is the method of choice when comparable changes in CBF are desired in both cerebral hemispheres.