Pharmacological characterization of mucin secretion from CHO-K1-hNK1R cells

Abstract

Numerous respiratory diseases increase mucin secretion from human airways. Several investigators hypothesize that mucin secretion from airway epithelium is NK1-receptor mediated. We have developed a mucin secretion assay using CHO-K1 cells transfected with the human NK1receptor (CHO-K1-hNK1R) that respond to NK1-specific agonists. Cells were labeled with [3H]-glucosamine and stimulated with agonists including Ac-[Arg6, Sar9, Met(O2)11] Substance P(6–11) (ASMSP; NK1-specific), [β-Ala8]-Neurokinin A(4–10) (BANK; NK2-specific), or human neutrophil elastase (HNE). Basal mucin secretion from CHO-K1-hNK1R and non-transfected cells was similar. Stimulation of CHO-K1-hNK1R, but not CHO-K1, with ASMSP or BANK concentration-dependently increased mucin secretion (pD2value[Emax] = 8.91±0.13[175%] and 7.56±0.05[100%], respectively). SR140333 (NK1antagonist), but not SR48968 (NK2antagonist), decreased ASMSP- and BANK-induced mucin release from CHO-K1-hNK1R. In these cells, endothelin-1, angiotensin II, serotonin, phenylephrine, senktide, and methacholine showed negligible effects on mucin 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-hNK1R with ASMSP and BANK causes robust and NK1-selective mucin release.