Bradykinin increases intracellular calcium levels in a human bronchial epithelial cell line via the B2 receptor subtype

Abstract.

Objective: To determine which types of kinin receptor are present in human bronchial epithelial cells we studied the capability of bradykinin to mobilize intracellular Ca²⁺ ([Ca²⁺] _i) in a human bronchial epithelial cell line (16HBE cells).¶Material: Human bronchial epithelial cell line transformed with an original defective simian virus 40 (SV40).¶Treatment: Bradykinin (0.1 pM to 0.1 μM), des-Arg⁹ bradykinin (1 μM), des-Arg¹⁰ kallidin (1 μM), indomethacin (1 μM), phosphoramidon (1 μM), captopril (1 μM), des-Arg⁹-[Leu⁸]bradykinin (1 μM), HOE 140 (DArg-[Hyp³, Thi⁵, DTic⁷, Oic⁸]-bradykinin) (1 μM), and NPC 16731 (DArg-[Hyp³, Thi⁵, DTic⁷, Tic⁸]-bradykinin) (1 μM).¶Methods: The mobilization of [Ca²⁺]_i was determined by the fura-2 method. Two sample Wilcoxon rank-sum (Mann-Whitney) test was used for statistical calculations.¶Results: Bradykinin, but not the selective agonists for kinin B₁ receptor des-Arg⁹ bradykinin and des-Arg¹⁰ kallidin, increased the mobilization of [Ca²⁺]_i (EC₅₀, 0.079 ± 0.009 nM) in 16HBE cells in a concentration-dependent manner. Pretreatment with the cyclooxygenase inhibitor indomethacin (1 μM) or the peptidase inhibitors, phosphoramidon (1 μM) or captopril (1 μM), did not affect the response to bradykinin. The kinin B₁ receptor antagonist, des-Arg⁹-[Leu⁸]bradykinin (1 μM), was inactive. HOE 140 and NPC 16731, two selective antagonists of the kinin B₂ receptor abolished the response to bradykinin (IC₅₀ of HOE 140 and NPC 16731 were 0.52 ± 0.037 nM and 1.67 ± 0.41 nM, respectively).¶Conclusions: The present data indicate the presence of kinin B₂ receptors in the 16HBE cells.