Blood-brain barrier preservation in the in vitro isolated guinea pig brain preparation.
The morphofunctional preservation of the blood-brain barrier (BBB) was evaluated in the isolated guinea pig brain maintained in vitro by arterial perfusion. Electron microscopy evaluation after 5 hr in vitro demonstrated that cerebral capillaries and BBB specializations in this preparation retain features compatible with structural integrity. BBB-impermeable and -permeable atropine derivatives arterially perfused to antagonize carbachol-induced fast oscillatory activity confirmed the functional preservation of the BBB in vitro. To study BBB function further, changes in extracellular K+ concentration during arterial perfusion of a high-K+ solution were measured with K+-sensitive electrodes positioned in the cortex and, as control, at the brain venous outlet, where the solution perfused through the brain arterial system was collected. After 5 hr in vitro, the [K+](o) values measured during high-K+ perfusion in the piriform and entorhinal cortices were 5.02 +/- 0.17 mM (mean +/- SE) and 5.2 +/- 0.21 mM, respectively (n = 6). Coperfusion of the high-K+ solution with the Na+/K+ pump blocker ouabain (10 microM; n = 4) induced consistently spreading depression preceded by a rise in [K+](o). Finally, sporadic, isolated spots of extravasation of the fluorescent marker fluorescein isothiocyanate (FITC)-dextran preferentially circumscribed to deep cortical layers was observed in brains perfused with FITC-dextran after 5 hr in vitro. The study demonstrates that the in vitro isolated guinea pig brain is viable for studying cerebrovascular interactions and BBB permeability of compounds active in the central nervous system.
Librizzi
L
L
Department of Neurophysiology, Istituto Nazionale Neurologico, via Celoria 11, 20133 Milan, Italy.
Janigro
D
D
De Biasi
S
S
de Curtis
M
M
D000818:Animals; D001285:Atropine / Q000378:metabolism / Q000494:pharmacology; D001286:Atropine Derivatives / Q000378:metabolism / Q000494:pharmacology; D001812:Blood-Brain Barrier; D002196:Capillaries / Q000378:metabolism; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D006168:Guinea Pigs; D018721:Muscarinic Agonists / Q000378:metabolism / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000378:metabolism / Q000494:pharmacology; D009924:Organ Culture Techniques / Q000379:methods*; D010477:Perfusion; D011188:Potassium / Q000378:metabolism
D001286:Atropine Derivatives; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D001285:Atropine; C006649:methylatropine; D002217:Carbachol; D011188:Potassium