ISSN:
1432-0533
Keywords:
Blood-brain barrier
;
Cortex
;
Lanthanum tracer
;
Potassium
;
Ion-selective micro-electrode
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Using lanthanum nitrate as a tracer, the permeability of rat cortical blood vessels was investigated during regional hypothermia of the cerebral cortex by electron microscopy. The concentration of K+ ions in the extracellular space of the cortex was determined using an ion-selective micro-electrode. Only at temperatures below about 7°C was an extravasation of tracer observed in a number of cortical capillaries and arterioles, where some of the tight junctions became widened and permeable. In a few cases penetration of the tracer into vacuoles of phagocytosing pericytes or macrophages was found. The extravasation of the tracer could mainly be observed in vessels on and below the cortical surface, less often in deeper cortical parts. At the same degree of hypothermia, the K+ concentration in the extracellular space increased, reaching a maximal value of ca. 6 mmol/l at a depth of about 200 μm. As could be shown in one previous experiment, the K+ concentration reached normal values again after rewarming to 37°C for 15 min, but an extravasation of the tracer was still observed. The role of the endothelial tight junctions and of the astrocytes together with the pericytes (or macrophages) is discussed regarding their importance for the effectiveness of the blood-brain barrier system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00688258
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