Pharmacological characterization of mucin secretion from CHO-K1-hNK(1)R cells

Numerous respiratory diseases increase mucin secretion from human airways. Several investigators hypothesize that mucin secretion from airway epitheli um is NK1-receptor mediated. We have developed a mucin secretion assay usin g CHO-K1 cells transfected with the human NK1 receptor (CHO-K1-hNK(1)R) tha t respond to NK1-specific agonists. Cells were labeled with [H-3]-glucosami ne and stimulated with agonists including Ac-[Arg(6), Sar(9), Met(O-2)(11)] Substance P(6-11) (ASMSP; NK1-specific), [beta-Ala(8)]-Neurokinin A(4-10) (BANK; NK2-specific), or human neutrophil elastase (HNE). Basal mucin secre tion from CHO-K1-hNK(1)R and non-transfected cells was similar. Stimulation of CHO-K1-hNK(1)R, but not CHO-K1, with ASMSP or BANK concentration-depend ently increased mucin secretion (pD(2) value[Emax] = 8.9(1)+/-0.1(3)[175%] and 7.56+/-0.05[100%], respectively). SR140333 (NK1 antagonist), but not SR 48968 (NK2 antagonist), decreased ASMSP- and BANK-induced mucin release fro m CHO-K1-hNK(1)R. In these cells, endothelin-1, angiotensin II, serotonin, phenylephrine, senktide, and methacholine showed negligible effects on muci n secretion. A similar lack of effect of these agonists was observed in non -transfected CHO-K1 cells. HNE increased mucin release four to five fold in both cell types. These studies demonstrate that stimulation of CHO-K1-hNK( 1)R with ASMSP and BANK causes robust and NK1-selective mucin release.