TY - JOUR
T1 - Rapid regulation of P-glycoprotein at the blood-brain barrier by endothelin-1
AU - Hartz, Anika M.S.
AU - Bauer, Björn
AU - Fricker, Gert
AU - Miller, David S.
PY - 2004/9
Y1 - 2004/9
N2 - The ATP-driven xenobiotic transporter P-glycoprotein is a critical element of the blood-brain barrier. To study regulation of P-glycoprotein function, we measured specific transport [(3′-oxo-4-butenyl-4-methyl-threonine(1), (valine(2)) cyclosporin (PSC833)-sensitive] of the fluorescent cyclosporin A derivative [N-ε(4-nitrobenzofurazan-7-yl)-D-Lys8]-cyclosporin A (NBDL-CSA) into the lumens of isolated rat brain capillaries using confocal microscopy and quantitative image analysis. Luminal NBDL-CSA accumulation was rapidly and reversibly reduced in a concentration-dependent manner by 0.1 to 100 nM endothelin-1 (ET-1). In this concentration range, ET-1 did not affect junctional permeability. The ETB receptor agonist sarafotoxin 6c also reduced transport. An ETB receptor antagonist blocked effects of ET-1 and sarafotoxin 6c; an ETA receptor antagonist was without effect. Consistent with this, immunostaining and Western blotting showed expression of the ETB receptor in brain capillary membranes. NBDL-CSA transport was also reduced by sodium nitroprusside, a NO donor, and by phorbol ester, a protein kinase C (PKC) activator. Inhibition of NO synthase (NOS) or PKC abolished the ET-1 effects. Thus, ET-1, acting through an ETB receptor, NOS, and PKC rapidly and reversibly reduced transport mediated by P-glycoprotein at the blood-brain barrier.
AB - The ATP-driven xenobiotic transporter P-glycoprotein is a critical element of the blood-brain barrier. To study regulation of P-glycoprotein function, we measured specific transport [(3′-oxo-4-butenyl-4-methyl-threonine(1), (valine(2)) cyclosporin (PSC833)-sensitive] of the fluorescent cyclosporin A derivative [N-ε(4-nitrobenzofurazan-7-yl)-D-Lys8]-cyclosporin A (NBDL-CSA) into the lumens of isolated rat brain capillaries using confocal microscopy and quantitative image analysis. Luminal NBDL-CSA accumulation was rapidly and reversibly reduced in a concentration-dependent manner by 0.1 to 100 nM endothelin-1 (ET-1). In this concentration range, ET-1 did not affect junctional permeability. The ETB receptor agonist sarafotoxin 6c also reduced transport. An ETB receptor antagonist blocked effects of ET-1 and sarafotoxin 6c; an ETA receptor antagonist was without effect. Consistent with this, immunostaining and Western blotting showed expression of the ETB receptor in brain capillary membranes. NBDL-CSA transport was also reduced by sodium nitroprusside, a NO donor, and by phorbol ester, a protein kinase C (PKC) activator. Inhibition of NO synthase (NOS) or PKC abolished the ET-1 effects. Thus, ET-1, acting through an ETB receptor, NOS, and PKC rapidly and reversibly reduced transport mediated by P-glycoprotein at the blood-brain barrier.
UR - http://www.scopus.com/inward/record.url?scp=4944230261&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=4944230261&partnerID=8YFLogxK
U2 - 10.1124/mol.104.001503
DO - 10.1124/mol.104.001503
M3 - Article
C2 - 15322229
AN - SCOPUS:4944230261
SN - 0026-895X
VL - 66
SP - 387
EP - 394
JO - Molecular Pharmacology
JF - Molecular Pharmacology
IS - 3
ER -