PMID- 10496952
OWN - NLM
STAT- MEDLINE
DCOM- 19991008
LR  - 20131121
IS  - 0026-895X (Print)
IS  - 0026-895X (Linking)
VI  - 56
IP  - 4
DP  - 1999 Oct
TI  - Characterization of human A(2B) adenosine receptors: radioligand binding, western
      blotting, and coupling to G(q) in human embryonic kidney 293 cells and HMC-1 mast
      cells.
PG  - 705-13
AB  - Recombinant human A(2B) adenosine receptors (A(2B)ARs) and receptors extended on 
      the amino terminus with hexahistidine and the FLAG epitope, DYKDDDDK (H/F-A(2B)) 
      were stably overexpressed (to >20,000 fmol/mg protein) in human embryonic kidney 
      293 cells (HEK-A(2B)). By Western blotting, the H/F-A(2B) receptor runs as a
      34.8-kDa glycoprotein. Pharmacological properties of A(2B)ARs were characterized 
      with (125)I-3-aminobenzyl-8-phenyl-(4-oxyacetic acid)-1-propylxanthine (K(D), 36 
      nM). In competition binding assays, the affinity of agonists is reduced by
      substitution on either the N(6)- or the C-2 position of the adenine ring, whereas
      5'-substitutions increase affinity, resulting in the potency order:
      5'-N-ethylcarboxamidoadenosine (NECA) >> N(6)-aminobenzyl-NECA approximately
      2-chloroadenosine > 2-[4-(2-carboxyethyl)phenethylamino]-NECA (CGS21680) >
      N(6)-aminobenzyladenosine. The A(2B)AR is potently blocked by the A(2A)-selective
      antagonist 4-(2-[7-amino-2-[2-furyl][1,2, 4]triazolo-[2,3-a][1,3,5]
      triazin-5-yl-amino]ethyl)phenol (ZM241385; K(I), 32 nM for A(2B), 1.4 nM for
      A(2A)) and the A(1) selective antagonist 8-cyclopentyl-1,3-dipropylxanthine
      (K(I), 50.5 nM for A(2B); 2.5 nM for A(1)). The K(I) values for the antiasthmatic
      xanthines, theophylline (7.8 microM) and enprofylline (6.4 microM), are below
      their therapeutic plasma concentrations (20 to 50 microM), and agree with K(I)
      determinations for inhibition of NECA-stimulated cAMP accumulation in HEK-A(2B)
      cells. NECA or N(6)-(2-iodo)benzyl-5'-N-methylcarboxamidodoadenosine (IB-MECA)
      stimulate inositol trisphosphates and calcium accumulation in HEK-A(2B) or
      HEK-A(3) cells, respectively, but only the A(3) response is prevented by
      pertussis toxin. In human HMC-1 mast cells, A(2B)AR activation stimulates calcium
      mobilization and cAMP accumulation. We conclude that HEK-A(2B) cells and HMC-1
      mast cells possess A(2B)AR glycoproteins that are coupled to both G(q/11) and
      G(s).
FAU - Linden, J
AU  - Linden J
AD  - Department of Internal Medicine, University of Virginia, Charlottesville,
      Virginia, USA. jlinden@virginia.edu
FAU - Thai, T
AU  - Thai T
FAU - Figler, H
AU  - Figler H
FAU - Jin, X
AU  - Jin X
FAU - Robeva, A S
AU  - Robeva AS
LA  - eng
GR  - R01-HK37942/HK/PHITPO CDC HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Mol Pharmacol
JT  - Molecular pharmacology
JID - 0035623
RN  - 0 (Anti-Asthmatic Agents)
RN  - 0 (Purinergic P1 Receptor Agonists)
RN  - 0 (Receptor, Adenosine A2B)
RN  - 0 (Receptors, Purinergic P1)
RN  - 0 (Xanthines)
RN  - 112533-64-9 (BW A522)
RN  - C137DTR5RG (Theophylline)
RN  - DT7DT5E518 (enprofylline)
RN  - E0399OZS9N (Cyclic AMP)
RN  - EC 3.1.4.- (Type C Phospholipases)
RN  - EC 3.6.1.- (GTP-Binding Proteins)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Anti-Asthmatic Agents/pharmacology
MH  - Blotting, Western
MH  - CHO Cells
MH  - Calcium/metabolism
MH  - Cell Degranulation/drug effects
MH  - Cells, Cultured
MH  - Cricetinae
MH  - Cyclic AMP/metabolism
MH  - GTP-Binding Proteins/*metabolism
MH  - Humans
MH  - Kidney/cytology/metabolism
MH  - Mast Cells/metabolism
MH  - Purinergic P1 Receptor Agonists
MH  - Radioligand Assay
MH  - Receptor, Adenosine A2B
MH  - Receptors, Purinergic P1/genetics/*metabolism
MH  - Theophylline/pharmacology
MH  - Type C Phospholipases/metabolism
MH  - Xanthines/metabolism/pharmacology/therapeutic use
EDAT- 1999/09/25 00:00
MHDA- 1999/09/25 00:01
CRDT- 1999/09/25 00:00
PHST- 1999/09/25 00:00 [pubmed]
PHST- 1999/09/25 00:01 [medline]
PHST- 1999/09/25 00:00 [entrez]
PST - ppublish
SO  - Mol Pharmacol. 1999 Oct;56(4):705-13.