Selective labelling of bradykinin receptor subtypes in WI38 human lung fibroblasts.
1. Binding of the B1 bradykinin receptor radioligand, [3H]-des-Arg10-kallidin (-KD) and the B2 receptor radioligand [3H]-bradykinin (-BK) was investigated in membranes prepared from WI38 human foetal lung fibroblasts. 2. One-site analysis of the saturation data for [3H]-des-Arg10-KD gave an equilibrium dissociation constant (KD) value of 0.51 +/- 0.12 nM and a maximum receptor density (Bmax) of 260 +/- 49 fmol mg-1 of protein. [3H]-des-Arg10-KD binding was displaced by ligands in the order: des-Arg10-KD > KD > > des-Arg9[Leu8]-BK > des-Arg9-BK > Hoe 140 > > BK, implying that it was binding selectively to B1 receptors. 3. One-site analysis of the binding of [3H]-BK to W138 membranes indicated that it had a KD value of 0.25 +/- 0.06 nM and a Bmax of 753 +/- 98 fmol mg-1 of protein. The potencies for displacement of [3H]-BK binding were: Hoe 140 > > BK = KD > > > des-Arg10-KD = des-Arg9[Leu8]-BK = des-Arg9-BK, which was consistent with binding to B2 receptors. 4. This is the first characterization of [3H]-des-Arg10-KD binding to include both kinetic and equilibrium data, and demonstrates that [3H]-des-Arg10-KD has a high affinity for human B1 bradykinin receptors and is sufficiently selective to be used as a radioligand for B1 receptors in human cells or tissues expressing an excess of B2 BK receptors.
Phagoo
S B
SB
Sandoz Institute for Medical Research, London.
Yaqoob
M
M
Brown
M C
MC
Burgess
G M
GM
D001920:Bradykinin / Q000031:analogs & derivatives / Q000378:metabolism*; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D011869:Radioligand Assay; D018002:Receptors, Bradykinin / Q000145:classification / Q000378:metabolism*; D014316:Tritium
D018002:Receptors, Bradykinin; D014316:Tritium; D001920:Bradykinin