title: Pharmacological characterization of bradykinin B1 and B2 receptors in IMR-90 and INT-407 human cell lines using a microphysiometer.
abstract: 1. In the present study, we used a microphysiometer to measure bradykinin-induced acidification responses in IMR-90, a human lung fibroblast cell line, and INT-407, a human colonic epithelial cell line. Furthermore, we investigated the effect of 24 h exposure of transforming growth factor (TGF)-alpha on the bradykinin response in INT-407 cells. 2. Bradykinin (0.1-100 nmol/L) was potent in producing acidification responses in IMR-90 cells (pEC50 8.79+/-0.13; Hill slope 0.96+/-0.04) and INT-407 cells (pEC50 8.90+/-0.04; Hill slope 1.00+/-0.07). These responses were competitively antagonized by the bradykinin B2 receptor antagonist icatibant in both IMR-90 cells (apparent pKB = 8.54+/-0.15; Hill slope = 1.09+/-0.13 and 1.66+/-0.26 in the absence and presence of 10 nmol/L icatibant, respectively) and INT-407 cells (pKB = 8.12+/-0.07 (3, 10 and 30 nmol/L icatibant); Hill slope = 1.06+/-0.04). However, the bradykinin B1 receptor antagonist des-Arg9Leu8-bradykinin (3 micromol/L) had no effect on the bradykinin responses. 3. The non-peptide bradykinin B2 receptor antagonist FR173657 selectively antagonized bradykinin-induced acidification responses in INT-407 cells in a competitive manner (pKB = 8.76+/-0.10; Hill slope = 0.92+/-0.05) at lower concentrations (1 and 3 nmol/L) but in an insurmountable manner at higher concentrations (10 nmol/L; Hill slope = 1.04+/-0.09). This compound, at concentrations of 10 and 100 nmol/L (Hill slope = 1.38+/-0.15), also proved to be an insurmountable antagonist in IMR-90 cells. 4. The bradykinin B1 receptor selective agonist Lys0des-Arg10-bradykinin (0.1 nmol/L to 0.1 micromol/L) failed to produce acidification responses in IMR-90 cells, even after 24 h pre-incubation with bacterial lipopolysaccharide (0.1 microg/mL). 5. A 24 h pre-incubation of INT-407 cells with TGF-alpha (1, 10 and 100 ng/mL) caused a significant concentration-dependent decrease in maximal bradykinin response without affecting the pEC50. 6. In addition to this study being the first to use a microphysiometer to characterize bradykinin B2 receptors in cultured IMR-90 human lung fibroblast cells and INT-407 human colonic epithelial cells, we also showed that pre-incubation of INT-407 cells with TGF-alpha caused a significant decrease in maximal acidification response mediated by bradykinin B2 receptors.
authors.affiliation: Department of Pharmacology, Monash University, Clayton Campus, Victoria, Australia.
authors.forename: K R
authors.initials: KR
authors.lastname: Bentley
authors.forename: B
authors.initials: B
authors.lastname: Jarrott
mesh_terms: D065168:Bradykinin Receptor Antagonists; D002460:Cell Line; D003106:Colon / Q000166:cytology / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000187:drug effects*; D016211:Transforming Growth Factor alpha / Q000494:pharmacology
chemical_list: D065168:Bradykinin Receptor Antagonists; C105311:FR 173657; D008070:Lipopolysaccharides; D011804:Quinolines; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; D016211:Transforming Growth Factor alpha