Functional characterization of adenosine transport across the BBB in mice.
We investigated transport characteristics of adenosine across the blood-brain barrier (BBB) in mice. Uptake clearance across the BBB was measured by using an in situ mouse brain perfusion technique and cultured mouse brain capillary endothelial cell line (MBEC4 cells). Nucleoside transporter was cloned by RT-PCR and expressed on Xenopus laevis oocyte. Both in situ and in vitro studies revealed that the adenosine uptake is concentration-dependent, Na(+)-independent and S-(p-nitrobenzyl)-6-thioinosine (NBMPR)-sensitive. The K(t) values of in situ and in vitro studies were 31.7 +/- 13.8 microM and 11.9 +/- 2.84 microM, respectively. A good correlation was found for the inhibitory effects of nucleoside analogs to adenosine uptake between in situ and in vitro studies. RT-PCR revealed the expression of RNA of mouse equilibrative nucleoside transporter (mENT1) in mouse brain capillary and MBEC4 cells. In mENT1 expressed on X. laevis oocyte, K(t) value of adenosine transport was 6.9 +/- 2.7 microM (and comparable to those in situ and in vitro studies). In conclusion, we characterized the adenosine transport across the BBB in mice by using in situ brain perfusion technique and MBEC4 cells and found that these transports share common characteristics with mENT1-mediated transport. Transport of adenosine across the BBB in mice may be attributable to mENT1.
Murakami
Hideyasu
H
Department of Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Ohkura
Airi
A
Takanaga
Hitomi
H
Matsuo
Hirotami
H
Koyabu
Noriko
N
Naito
Mikihiko
M
Tsuruo
Takashi
T
Ohtani
Hisakazu
H
Sawada
Yasufumi
Y
D000241:Adenosine / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D051379:Mice; D014982:Xenopus laevis
D000241:Adenosine