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Blood-brain barrier permeability during shortlasting intravascular hyperosmolality
European Journal of Clinical Investigation
|December 1, 1978
Summary
Transient intravascular hyperosmolality did not alter blood-brain barrier permeability to sodium and chloride ions. Water permeability remained stable, though water extraction increased with hypertonic agents like mannitol and contrast media.
Area of Science:
- Neuroscience
- Physiology
- Pharmacology
Background:
- The blood-brain barrier (BBB) tightly regulates the passage of substances into the brain.
- Understanding BBB permeability is crucial for drug delivery and neurological disease research.
- Intravascular hyperosmolality is a potential method to transiently alter BBB function.
Purpose of the Study:
- To investigate the effect of short-lasting intravascular hyperosmolality on blood-brain barrier permeability to ions and water.
- To determine if hyperosmolality induces a significant 'opening' of the BBB.
Main Methods:
- Utilized the double indicator single injection method in 25 patients.
- Induced hyperosmolality via rapid injection into the internal carotid artery.
- Administered hypertonic solutions: 5% saline, 25% mannitol, or metrizoate contrast medium (Isopaque-amine 280).
Main Results:
- Sodium (24Na+) and chloride (36Cl-) ion extraction remained unchanged and near zero, indicating no BBB opening.
- Blood-brain barrier permeability to water (3HOH) was unaffected by hyperosmolality itself.
- Water extraction increased with mannitol and Isopaque-amine 280, correlating with their lower water concentrations.
Conclusions:
- Short-lasting intravascular hyperosmolality does not compromise the blood-brain barrier's integrity for small ions.
- The BBB's permeability to water is not significantly altered by hyperosmolality, but influenced by the osmotic agent's water content.
- These findings suggest that hyperosmotic agents can be used cautiously without causing widespread BBB disruption.