Bradykinin and Respiratory Mucous Membranes: Analysis of Bradykinin Binding Site Distribution and Secretory ResponsesIn VitroandIn Vivo

Abstract

Bradykinin (BK) and lysyl-BK (lys-BK, kallidin) have been proposed as potentially important mediators of rhinorrhea. Possible mechanisms by which BK might contribute to rhinorrhea were investigated by several approaches. (1) The autoradiographic distribution of 125I-BK binding sites in human inferior turbinate nasal mucosa was determined. (2) The effects of BK and lys-BK and antagonists on radiolabeled respiratory glycoconjugate (RGC) release from human nasal mucosa was measured. (3) The secretory effects of BK were studied in cat tracheal mucosa maintained in short-term explant culture, and in ferret trachea maintained in Ussing chambers. (4) The effects of BK on macromolecule secretion in guinea pig nasal mucosa was studied in vivo. Autoradiographic examination of human nasal mucosa revealed that 125I-BK specifically bound to small muscular arteries, venous sinusoids, and submucosal fibers. No specific binding to submucosal glands or goblet cells was noted. Human nasal fragments secreted significantly increased amounts of RGC in response to 10 microM BK (15.0% +/- 1.8 compared with control values; mean +/- standard error of the mean; n = 7; p less than 0.01 by Student's unpaired t test), 10 microM lys-BK (12.2% +/- 3.3; n = 5; p less than 0.05), and 100 microM methacholine (35.7% +/- 2.3; p less than 0.0001). The addition of 1 microM BK, or 1 microM lys-BK, did not induce release. The addition of the BK receptor antagonist des-Arg9-[Leu8]-BK (10 microM) or inhibition of arachidonic acid metabolism with 50 microM nordihydroguaiaretic acid or 65 microM ibuprofen inhibited the prosecretory effect of 10 microM BK.(ABSTRACT TRUNCATED AT 250 WORDS)