BRADYKININ INCREASES INTRACELLULAR CALCIUM LEVELS IN A HUMAN BRONCHIAL EPITHELIAL CELL LINE VIA THE B2 RECEPTOR SUBTYPE

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.