Comparisons of P-glycoprotein expression in isolated rat brain microvessels and in primary cultures of endothelial cells derived from microvasculature of rat brain, epididymal fat pad and from aorta.
In vivo expression of P-glycoprotein in isolated rat brain microvessels is compared with that in vitro in primary cultures of brain endothelial cells. More P-glycoprotein is detected by Western immunoblotting in microvessels than in cultured endothelium. RT-PCR with isoform-specific primers and immunoblotting with a mdr1b-specific antibody reveals only mdr1a in vivo but both mdr1a and mdr1b in vitro. Thus mdr1a decreases whereas mdr1b increases during culture. P-Glycoprotein activity is evident in vitro, with resistance modulators, e.g. verapamil, producing increases in intracellular [3H]vincristine accumulation. Endothelial cells cultured from epididymal fat pad microvasculature and aorta contain little or no P-glycoprotein. Here, resistance modulators are less effective.
Barrand
M A
MA
Department of Pharmacology, University of Cambridge, UK.
Robertson
K J
KJ
von Weikersthal
S F
SF
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000187:drug effects; D017667:Adipocytes / Q000166:cytology; D000818:Animals; D001011:Aorta / Q000166:cytology; D001483:Base Sequence; D001921:Brain / Q000098:blood supply / Q000166:cytology; D002196:Capillaries / Q000378:metabolism; D002478:Cells, Cultured; D003603:Cytotoxins / Q000494:pharmacology; D017931:DNA Primers; D004317:Doxorubicin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004822:Epididymis / Q000166:cytology; D008297:Male; D008969:Molecular Sequence Data; D051381:Rats; D017208:Rats, Wistar; D014700:Verapamil / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D003603:Cytotoxins; D017931:DNA Primers; D014750:Vincristine; D004317:Doxorubicin; D014700:Verapamil