Cerebromicrovascular endothelial cells are resistant to L-glutamate.
Cerebral microvascular endothelial cells (CMVECs) have recently been implicated as targets of excitotoxic injury by l-glutamate (l-glut) or N-methyl-d-aspartate (NMDA) in vitro. However, high levels of l-glut do not compromise the function of the blood-brain barrier in vivo. We sought to determine whether primary cultures of rat and piglet CMVECs or cerebral microvascular pericytes (CMVPCs) are indeed sensitive to l-glut or NMDA. Viability was unaffected by 8-h exposure to 1-10 mM l-glut or NMDA in CMVECs or CMVPCs isolated from both species. Furthermore, neither 1 mM l-glut nor NMDA augmented cell death induced by 12-h oxygen-glucose deprivation in rat CMVECs or by 8-h medium withdrawal in CMVPCs. Additionally, transendothelial electrical resistance of rat CMVEC-astrocyte cocultures or piglet CMVEC cultures were not compromised by up to 24-h exposure to 1 mM l-glut or NMDA. The Ca(2+) ionophore calcimycin (5 microM), but not l-glut (1 mM), increased intracellular Ca(2+) levels in rat CMVECs and CMVPCs assessed with fluo-4 AM fluorescence and confocal microscopy. CMVEC-dependent pial arteriolar vasodilation to hypercapnia and bradykinin was unaffected by intracarotid infusion of l-glut in anesthetized piglets by closed cranial window/intravital microscopy. We conclude that cerebral microvascular cells are insensitive and resistant to glutamatergic stimuli in accordance with their in vivo role as regulators of potentially neurotoxic amino acids across the blood-brain barrier.
Domoki
Ferenc
F
Dept. of Physiology and Pharmacology, Wake Forest Univ. Health Sciences, Medical Center Blvd, Hanes Bldg 1052, Winston-Salem, NC 27157-1010, USA. fdomoki@wfubmc.edu
Kis
Béla
B
Gáspár
Tamás
T
Bari
Ferenc
F
Busija
David W
DW
D000818:Animals; D000831:Animals, Newborn; D001160:Arterioles / Q000187:drug effects / Q000503:physiopathology; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001920:Bradykinin / Q000494:pharmacology; D001921:Brain / Q000098:blood supply / Q000166:cytology / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D004351:Drug Resistance; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000097:blood / Q000494:pharmacology*; D006935:Hypercapnia / Q000503:physiopathology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology; D062793:Occludin; D020286:Pericytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D034421:Sus scrofa; D062826:Zonula Occludens-1 Protein
D008565:Membrane Proteins; C409466:NR1 NMDA receptor; D062793:Occludin; C568987:Ocln protein, rat; D010750:Phosphoproteins; D016194:Receptors, N-Methyl-D-Aspartate; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D018698:Glutamic Acid; D016202:N-Methylaspartate; D001920:Bradykinin