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Selective labelling of bradykinin receptor subtypes in WI38 human lung fibroblasts
Author(s) -
Phagoo Stephen B.,
Yaqoob Mohammed,
Brown Michael C.S.,
Burgess Gillian M.
Publication year - 1996
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1996.tb15752.x
Subject(s) - radioligand , bradykinin , receptor , dissociation constant , radioligand assay , kallidin , chemistry , binding site , biology , microbiology and biotechnology , medicine , biochemistry , kinin
1 Binding of the Bj bradykinin receptor radioligand, [ 3 H]‐des‐Arg 10 ‐kallidin (‐KD) and the B 2 receptor radioligand [ 3 H]‐bradykinin (‐BK) was investigated in membranes prepared from WI38 human foetal lung fibroblasts. 2 One‐site analysis of the saturation data for [ 3 H]‐des‐Arg 10 ‐KD gave an equilibrium dissociation constant ( K D ) value of 0.51 ± 0.12 nM and a maximum receptor density (B max ) of 260 ± 49 fmol mg −1 of protein. [ 3 H]‐des‐Arg 10 ‐KD binding was displaced by ligands in the order: des‐Arg 10 ‐KD > KD > > des‐Arg 9 [Leu 8 ]‐BK > des‐Arg 9 ‐BK > Hoe 140 > > BK, implying that it was binding selectively to B 1 receptors. 3 One‐site analysis of the binding of [ 3 H]‐BK to WI38 membranes indicated that it had a K D value of 0.25 ± 0.06 nM and a B max of 753 ± 98 fmol mg −1 of protein. The potencies for displacement of [ 3 H]‐BK binding were: Hoe 140 > > BK = KD > > > des‐Arg 10 ‐KD = des‐Arg 9 [Leu 8 ]‐BK = des‐Arg 9 ‐BK, which was consistent with binding to B 2 receptors. 4 This is the first characterization of [ 3 H]‐des‐Arg 10 ‐KD binding to include both kinetic and equilibrium data, and demonstrates that [ 3 H]‐des‐Arg 10 ‐KD has a high affinity for human B 1 bradykinin receptors and is sufficiently selective to be used as a radioligand for B 1 receptors in human cells or tissues expressing an excess of B 2 BK receptors.