High expression of nitrobenzylthioinosine-insensitive dipyridamole binding sites in postmortem human ependymal tissue.
The presence of both nitrobenzylthioinosine-sensitive and nitrobenzylthioinosine-insensitive dipyridamole binding sites in postmortem human ependymal tissue is reported. Displacement studies using 15 nM [3H]dipyridamole revealed 50-60% of the sites were sensitive to nitrobenzylthioinosine. Non-linear analysis of binding isotherms to estimate the density of nitrobenzylthioinosine-sensitive and -insensitive sites revealed a maximum number of nitrobenzylthioinosine-sensitive binding sites (Bmax) of 395 +/- 19 fmol/mg protein and a nitrobenzylthioinosine-insensitive Bmax of 3910 +/- 700 fmol/mg protein (corresponding Kd values of 0.1 nM and 114 nM respectively). Thus there are approximately 10 times as many nitrobenzylthioinosine-insensitive sites as nitrobenzylthioinosine-sensitive [3H]dipyridamole binding sites in human ependymal membranes.
Jones-Humble
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Wellcome Research Laboratories, Burroughs Wellcome Co., Research Triangle Park, NC 27709.
Morgan
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D000328:Adult; D000345:Affinity Labels; D000368:Aged; D000369:Aged, 80 and over; D001665:Binding Sites / Q000187:drug effects; D004176:Dipyridamole / Q000378:metabolism*; D004805:Ependyma / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D013868:Thioinosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000345:Affinity Labels; D013868:Thioinosine; D004176:Dipyridamole; C001789:4-nitrobenzylthioinosine