Assay for inhibitors of nucleoside transport based upon the use of 5-(/sup 125/I)IODO-2'-deoxyuridine (IdUrd) as permeant

Conference · Sat Mar 01 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5326789

Mahony, W B; Zimmerman, T P

/sup 125/IdUrd has been shown to permeate human erythrocytes via the same carrier that transports physiological nucleosides. Like Urd and dThd, IdUrd was metabolically inert in the erythrocytes. Initial velocities (20/sup 0/C) of /sup 125/IdUrd transport were linear for approx.2s, yielding a K/sub m of 73 +/- 18 ..mu..M (n = 6). Ado inhibited /sup 125/IdUrd transport competitively with a K/sub i/ of 32 +/- 2 ..mu..M (n = 2). Submicromolar concentrations of high-affinity inhibitors of nucleoside transport, such as 6-((4-nitro-benzyl) thio)-9-..beta..-D-ribofuranosylpurine (NBMPR), dilazep and dipyridamole, blocked /sup 125/IdUrd transport. However, this activity of NBMPR could not be characterized by steady-state kinetics due to nonlinear initial velocities observed when /sup 125/IdUrd and NBMPR were added simultaneously to the cells. For this reason, high-affinity inhibitors were characterized in terms of their 50% inhibitory concentrations towards /sup 125/IdUrd transport: NBMPR 24 nM; dilazep, 88 nM; dipyridamole, 480 nM. The use of /sup 125/IdUrd as inhibitors of nucleoside transport by allowing the cell pellets generated in these assays to be counted directly in a gamma spectrometer, thereby circumventing the solubilization and decolorization of cell pellets required by assays that use /sup 3/H- or /sup 14/C-labeled nucleoside permeants.

• Research Organization: Wellcome Research Labs., Research Triangle Park, NC
• OSTI ID: 5326789
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:3
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ANTIMETABOLITES
AZINES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
DAYS LIVING RADIOISOTOPES
DEOXYURIDINE
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ERYTHROCYTES
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INHIBITION
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MATERIALS
MEMBRANE TRANSPORT
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PERMEABILITY
PYRIMIDINES
RADIOASSAY
RADIOISOTOPES
REACTION KINETICS
RIBOSIDES
TRACER TECHNIQUES
URACILS