| In Vitro | In vitro activity: Measurement of Inositol Phosphate Accumulation in MRC5 Fibroblasts. [3H]Inositol phosphate1 accumulation was measured in MRC5 fibroblasts labeled with [3H]myoinositol according to the method described by Oury-Donat et al. (1994). Cells cultured in 6-well plates were labeled for 48 h with 5 μCi/ml [3H]myoinositol added to the culture medium (DMEM). Cells were then incubated for 4 h in DMEM containing 0.5 μg/ml IL-1β to induce B1 receptor synthesis. Agonist stimulation of inositol phosphate 1 accumulation was performed in DMEM containing 50 mM LiCl and test compounds. Antagonists were added 15 min before 10 nM Lys0-des-Arg10BK. After 30 min of incubation at 37°C, the medium was discarded, and the reaction was stopped by rapid addition of 1 ml of cold methanol and 1 N HCl (v/v). The cells were scraped, and the suspension was transferred to a glass tube with 1 ml of chloroform and 20 μl of 12 N HCl. The aqueous phase was neutralized by 350 μl of 1 M NaHCO3 and applied to 1 ml of Dowex AG1 × eight columns. [3H]inositol phosphate 1 was eluted with 0.2 M ammonium formate and 0.1 M formic acid. Radioactivity was measured by liquid scintillation spectrometry.
Kinase Assay: Assay of [3H]Lys0-des-Arg9-BK Binding to B1 Receptors. MRC5 human fibroblasts (American Type Culture Collection, Manassas, VA) and transfected HEK-293 cells expressing human B1receptors were routinely grown in Dulbecco's modified Eagle's medium (DMEM) with Glutamax-I (Life Technologies, Cergy Pontoise, France) supplemented with 10% fetal calf serum (Life Technologies) and antibiotics. MRC5 were incubated for 4 h in DMEM containing 0.5 μg/ml interleukin-1β (IL-1β) to induce B1 receptor synthesis. Cells were scraped and homogenized for 1 min using a Polytron (setting 8) in 25 mM TES-HCl containing 1 mM 1-10 phenantrolin. Homogenates were centrifuged at 40,000g for 15 min at 4°C, and pellets were resuspended in the same buffer using the Polytron (setting 8) for 1 min. Membranes were pelleted at 40,000g for 10 min at 4°C, resuspended in the same buffer, and conserved at -80°C.
Cell Assay: SSR240612 is a potent bradykinin B1 receptor antagonist, with Kis of 0.48 nM and 0.73 nM for B2 kinin receptors of human fibroblast MRC5 and HEK cells expressing human B1 receptors, 481 nM and 358 nM for B1 receptors of guinea pig ileum membranes and CHO cells expressing human B1 receptor, respectively. SSR240612 inhibits inositol phosphate 1 formation with an IC50 of 1.9 nM, but shows no obvious effect on inositol phosphate-1 formation induced by BK (3 nM) activation of B2 receptor in human fibroblast MRC5. |
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| In Vivo | Des Arg9-BK-Induced Mice Paw Edema. Groups of eight male albino mice under isoflurane anesthesia received a 20-μl intraplantar injection into the right hind paw of 5 μg of IL-1β in phosphate-buffered saline/0.1% BSA. Forty minutes later (T = 0), mice received, under anesthesia, a 20-μl intraplantar injection in the same paw of des-Arg9-BK (10 μg/paw) in water. SSR240612 or vehicle [5% (v/v) ethanol and 5% (v/v) Tween 80 in water] was administered by oral route at the doses of 1, 3, and 10 mg/kg 1 h before des-Arg9-BK injection and by intraperitoneal route at the doses of 0.1, 0.3, and 1 mg/kg 40 min before des-Arg9-BK injection. Paw volume was measured with a plethysmometer at T = -2 h (initial measurement) and at several times after edema induction (T = 20, 40, 60, and 120 min). Paw edema volume was expressed in milliliters as the difference between the paw volume at each time after edema induction and the initial paw volume. Results for each group are expressed as mean ± S.E.M. of individual paw edema volumes. Statistical analysis was performed after verification of normality and homogeneity of variances using repeated ANOVA, then Duncan's test, treated groups versus des-Arg9-BK control group. |
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