Lipopolysaccharide decreases bradykinin receptor-induced acidification responses in cultured bovine aortic endothelial cells.
The effects of bacterial lipopolysaccharide (Escherichia coli 0127-B8) on bradykinin receptor function in bovine aortic endothelial cells were investigated using a microphysiometer. Bradykinin and Lys(0)-desArg(10)-bradykinin produced concentration-dependent acidification responses with pEC(50) values of 8.87+/-0.20 and 9.78+/-0.08, respectively. These responses were competitively and selectively antagonised by the bradykinin B(2) receptor antagonist, icatibant and the bradykinin B(1) receptor antagonist, desArg(9)-Leu(8)-bradykinin, respectively. The non-peptide bradykinin B(2) receptor antagonist, FR173657 (0.3 and 3 nM), selectively antagonised bradykinin-induced acidification responses, causing rightward shifts of the concentration-response curves to bradykinin, but at the same time, significantly decreasing the maximum response. A preincubation with lipopolysaccharide (0.01 and 0.1 microg/ml) for 24 h caused a significant concentration-dependent decrease in maximal response to bradykinin (27.2+/-1.9 and 9.7+/-0.4% of control) and the bradykinin B(1) receptor agonist, Lys(0)-desArg(10)-bradykinin (59.0+/-7.14 and 25.3+/-7.8% of control), without affecting the EC(50). These results suggest that bradykinin B(1) receptors are constitutively expressed in cultured bovine aortic endothelial cells and that the microphysiometer provides a rapid, sensitive technique to characterise bradykinin receptors and investigate their regulation by cytokines. Interactions between bradykinin receptors and lipopolysaccharide may play a part in the cascade of deleterious effects that occur during septic shock.
Department of Pharmacology, PO Box 13E, Monash University, Monash, Vic 3800, Australia. kim.bentley@med.monash.edu.au
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D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology; D065168:Bradykinin Receptor Antagonists; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004731:Endotoxins / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000187:drug effects*
D065168:Bradykinin Receptor Antagonists; D004731:Endotoxins; C105311:FR 173657; D008070:Lipopolysaccharides; D011804:Quinolines; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; C051090:bradykinin, Leu(8)-des-Arg(9)-; C044101:endotoxin, Escherichia coli; D001920:Bradykinin