Characterization of bradykinin receptors in guinea pig gall bladder.
Specific binding of [3H]bradykinin (BK) to guinea pig gall bladder (GPGB) membranes was protein dependent, rapid (Kon = 0.067 min-1) with high affinity (Kd = 0.45 +/- 0.02; n = 3), saturable (Bmax = 546 +/- 56 fmol/mg of protein) and showed no cooperativity (nH = 1.19 +/- 0.08). A BK B2 receptor type was indicated by the rank order of potency for inhibition of binding by B2 antagonists, [(D)Arg-[Hyp3,Thi5,(D)Tic7-Oic8]-bradykinin (HOE140) > (D)Arg-[Hyp3,(D)HypE(transpropyl)7-Oic8]-bradykinin (NPC17731) > (D)Arg-[Hyp3,Thi5, (D)Tic7-Tic8]-bradykinin (NPC16731) > (D)Arg-[Hyp3,(D)Phe7]-bradykinin (NPC567)] and agonists (BK = kallidin = Tyr(Me)8-BK > Tyr8-BK,> Hyp4-kallidin) as well as inactivity of the B1 agonist des(Arg9)-BK. Nonhydrolyzable GTP analogs (GTP-gamma-S and guanylyl-5'-imido-diphosphate) produced 80% inhibition of specific binding suggesting receptor coupling to guanine nucleotide-binding proteins. BK increased polyphosphoinositide hydrolysis in chopped GPGB in a concentration-dependent manner (0.01-300 microM; EC50 = 414 +/- 171 nM; n = 3-9 tissues/concentration). HOE140 and NPC16731, inhibited BK-induced polyphosphoinositide hydrolysis but only the latter appeared competitive (pKb 8.09 +/- 0.19, n = 3). U73122, an inhibitor of phospholipase C pathway, also inhibited BK-induced turnover in GPGB (IC50 = 46.9 +/- 17.3 nM). BK produced a concentration-related contraction of isolated strips of GPGB. Indomethacin significantly decreased both the potency and efficacy of BK whereas thiorphan, a neutral endopeptidase inhibitor, and/or captopril, an angiotensin-converting enzyme inhibitor, enhanced potency.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Pharmacology, Zeneca Pharmaceuticals Group, Business Unit of ZENECA Inc., Wilmington, Delaware.
R C
RC
Falcone
S J
SJ
Hubbs
J D
JD
Vanderloo
J C
JC
Prosser
J
J
Little
B
B
Gomes
D
D
Aharony
R D
RD
Krell
D000595:Amino Acid Sequence; D000818:Animals; D001920:Bradykinin / Q000037:antagonists & inhibitors / Q000378:metabolism; D004355:Drug Stability; D005704:Gallbladder / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D006168:Guinea Pigs; D006868:Hydrolysis; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D011869:Radioligand Assay; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D014316:Tritium
D010455:Peptides; D010716:Phosphatidylinositols; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter; D014316:Tritium; D001920:Bradykinin