Effect of bradykinin on prostaglandin production by human skin fibroblasts in culture

Human eosinophil-granule major basic protein and synthetic polycations induce airway hyperresponsiveness in vivo dependent on bradykinin generation

In the current series of experiments we investigated the role of bradykinin in airway hyperresponsiveness induced by human eosinophil-granule major basic protein (MBP). Bronchoalveolar lavage was performed after intratracheal instillation of MBP or poly-L-lysine in anesthetized, intubated rats, and levels of immunoreactive kinins and kallikrein-like activity were determined. Both MBP and poly-L-lysine induced a three- and eightfold increase in levels of kallikrein-like activity and i-kinins, respectively. To determine whether kinin production is required for the development of airway hyperresponsiveness induced by cationic proteins, dose-response curves to methacholine were constructed before and 1 h after intratracheal instillation of either MBP or poly-L-lysine (100 micrograms). MBP and poly-L-lysine induced an increase in airway responsiveness, which was inhibited by pretreatment with a selective BK-2 receptor antagonist, NPC 17713 (250 micrograms/ml). Our results demonstrate that MBP and poly-L-lysine activate kallikrein and stimulate the generation of i-kinins in vivo, an effect that may be related to the cationic charge of these proteins. Furthermore, the ability of these proteins to increase airway responsiveness appears to be dependent on the generation of i-kinins.

Effect of bradykinin on intracellular signalling systems in a rat clonal dental pulp-cell line

The cloned pulp-cell line RDP4-1 increases cAMP production, hydrolyses phosphoinositide (PI) and mobilizes calcium in response to prostaglandin E2 (PGE2) and PGF2-alpha. The effect of bradykinin (BK) on intracellular signalling systems and DNA synthesis was studied in these cells. BK (10 microM) transiently increased cytoplasmic free calcium ([Ca2+]i) both in the presence and absence of external calcium. After stimulation with BK (10 microM), cells did not respond significantly to PGE2 (0.5 microgram/ml). Pretreatment with indomethacin (30 microM) inhibited the [Ca2+]i increment by BK (10 microM), but not by the subsequent addition of PGE2 (0.5 micrograms/ml). Also, pretreatment with PGE2 (0.5 microgram/ml) blocked the action of BK (10 microM), BK (0.1-100 microM) stimulated PI hydrolysis and cAMP production in a dose-dependent manner. Both the PI and the cAMP responses were inhibited by indomethacin (30 microM), as was the calcium response. BK (0.01-10 microM) also stimulated release of arachidonic acid and its metabolites dose-dependently. However, prolonged exposure to BK in serum-deficient medium did not exert any effect on DNA synthesis. RDP 4-1 cells, therefore, appear to respond to BK with increased cAMP production. PI hydrolysis and calcium mobilization. The inhibition of these effects of BK by indomethacin raises the possibility that cyclo-oxygenase product(s), especially PGE2 or PGE2-like compounds, may be responsible for evoking these effects. These results indicate that BK may stimulate or modulate cell metabolism in the dental pulp.

[Hyp3]-bradykinin and [Hyp3]-Lys-bradykinin interact with B2-bradykinin receptors and stimulate inositol phosphate production in cultured human fibroblasts

The recently isolated, naturally occurring peptide hormones [Hyp3]-bradykinin and [Hyp3]-Lys-bradykinin were investigated for their agonist activity on solubilized binding sites from human fibroblasts. Both ligands competed with [3H]bradykinin binding in a dose-dependent fashion with potencies similar to bradykinin (BK) and Lys-BK. Biological activity was assessed by determination of inositol phosphate accumulation and cyclic 3',5'-adenosine monophosphate synthesis in intact cultured cells. Stimulation by the hydroxylated peptides resulted in a pronounced accumulation of both parameters with similar effectiveness as BK and Lys-BK. These results indicate that [Hyp3]-BK and [Hyp3]-Lys-BK are agonists at the bradykinin receptor system with properties comparable to their non-hydroxylated analogues. This suggests that hydroxylation of kinins does not alter receptor interaction or signal transduction in cultured human fibroblasts.